I'm so glad that Vox didn't die at the end of season 2, not even just because he kicks ass as a villain and I love him, but moreso from a long-term narrative standpoint
Because if they just killed Vox how they did with Adam. I would've began to get really concerned that they would just kill each season's main villain which would've just became way too predictable and would kill the stakes of each season, because if we know the villian will die at the end if each season then the stakes are lowered because you know you only have a limited time with them before they're just... gone.
If you're going to kill a character, the biggest thing you need to consider is if the impact on the long term narrative would be more interesting rather then less interesting if they were killed off. (I'm talking about being killed for good, so, no, Pentious doesn't really count)
Adam's death has drastic changes on the future of the story far moreso then if he was kept alive but seriously injured, or if he just fucked off and fled. It ended the exterminations, Sera finally began to reflect on everything, it majorly fucked Lute up, and proving Angels could be killed changes everything throughout the future of the show. It's what Vox uses in the first place.
It's probably the most critical for Lute's downward spiral, as they are clearly setting something up long term for her for multiple seasons. You could aruge keeping Adam alive would've made Heaven's approach to redeemed sinners more interesting, but you cannot really aruge that his death's impact on Lute would've made her long term narrative better imp. Adam being dead is the major turning point for Lute that clearly will have the most long term consequences, instead of the somewhat short term consequences that it had on everyone else.
But The reason why killing Vox wouldn't really work because killing one of the Vees is kind of like killing all of the Vees. The Vees work so well because they're literally evil found family. When the Vees can cooperate, they legitimately can be the most dangerous threat there is. There's a lot to explore with all three of them, not just with each other, but with the characters outside them.
If Vox was killed, I don't think it would better long term route for Alastor compared to if Vox is still alive. Which is the opposite case for Lute. Alastor probably wouldn't become more unstable if Vox was gone for good. He likely would become more unstable because Vox is still around even after all that. If Vox dies, Alastor will always assume he was always right about Vox, when he actually isn't. So it would be way more interesting for Alastor to have to realize that Vox actually is different now then what he thought he always was. And Alastor would probably not like having to face that reality over just being bored without Vox and his death confirming his beliefs the whole time.
And For Valentino and Velvette; it would sort of feel like a betrayal of their characters for them to have not saved one of their own. It would also make the Vees trying to fix their reputation a total non-issue long term. Because it's much easier to fix it up if Vox is dead rather then having the Vees and Vox try to restore his public image. It's also far more interesting to see Vox be forced to live just to deal with the consequences of what he had just done. Not only to himself, but to the ones he cares most about. If Vox was killed, we don't get that at all. Most of Hell would move on quickly or be glad if he was dead at this current time. Making Vox live having to not only be forced having to pick up his own pieces, but having to watch Valentino and Velvette also pick up his pieces, is a better long term narrative route ot go.
Basically, what I'm saying is keeping Vox alive, but gravely injured/and weakened makes way more sense long term then him dying at the end of season 2. Because if it becomes predictable that every main villain will always die... then that's boring af. You start a new season, see the new villain, and immediately know "Well we only got like 8 more episodes of this fucker."
So not knowing whether or not the main villain will die during each season one of the best things they could've done for the long term narrative and viewer enjoyment; especially for this kind of show. It does work in some shows to always kill your main villain each season, but not a show like Hazbin. (Hard to explain why tho)
This is the main reason I really disagree when anyone says Vox should've died instead of having the Vees save him. Like having Vox dead would be way worse for the long term narrative then keeping him alive. People cannot handle not having instant gratification anymore and it shows. (This is legitimately the biggest reason why I miss cable)
And unpopular opinion, I don't want them to kill off Valentino, either. Like, I know a lot of people want him to die because they hate that he does to Angel, and don't get me wrong I hate what he does to Angel, too. But let's be serious here, killing a character solely because you know the audience will hate what evil things he does is not good writing if you know the story will actually benefit from keeping him alive. Dare I say, keeping Valentino alive is much more interesting for both their characters then just killing Valentino. It's the boring route of trying to make Angel's life better imo. If Angel is only freed because Valentino died then leaving Valentino wouldn't be Angel's choice. I would find it way more satisfying if Angel was able to break free of his chain the same way Alastor was able to.
Not to mention I do think the theory that Angel's redemption will end up being due to having the chance to kill Valentino like he did with his father, but choosing not to despite everything Valentino is the most likely route we're going with him. That is way way more interesting then Angel just killing Valentino or someone else killing Valentino. I don't care who would kill him because I can't think of any character that would make it work for both Angel and Valentino's long term arcs. Not even Lute.
I think Valentino have to deal with the fact that Angel is free and especially is completely out of reach in Heaven is a way more fitting punishment then just... dying. The crashout he would have and then Vox and Velvette having to calm him down, pick up his pieces, and and try to make him move on so they can return to normal operations (and life) would be way more interesting compared to him just being killed for the awful shit he did to Angel.
And for Angel, I feel like it would be way more interesting to for Angel to have made it to heaven, but Valentino to be alive in Hell, and the show habing explore the incredibly difficult and awful feeling fact that even when you finally have the chance to truly leave abuse and are in a safe place, that it ends up feeling wrong that you're safe and away from the abuser, because that life with your abuser became so normal. You end up missing what was normal for so long, even though you know it was bad, and you feel ashamed for even having those thoughts, and that feeling is way more intense if your abuser is alive and you left them compared to them being dead while you're still with them. (They kind of explored this idea with Pentious missing Hell because his friends were back there, but missing your friends is completely different then missing your abuser)
Now, the latter can also work in a narrative setting, TADC did it with Jax and Gangle after Jax died, but Hazbin is a completely different show. Valentino and Angel are completely different people compared to Jax and Gangle and their dynamic is different. And what worked for their abusive elationship will NOT be the best way to go about Valentino and Angel's. (for context I love the TADC finale)
So yeah, I think that exploring how Valentino reacts when Angel is permanently out of reach and how that effects his relationship with the other Vees and their reputation as a whole is way more interesting then. "Valentino is dead now let's see how Vox and Velvette handle his death now that he's not here." Because Valentino being alive and Angel being gone will especially effect Vox and Val's relationship. It will also even effect Vox and Angel's relationship
I also think it's incredibly important for Velvette's long term arc because we are not aware of how much she is aware of Vox and Valentino's past with Alastor and Angel respectively, so in order for her to connect to them and understand them better, she has to understand what happened to them, and she'll also offer a fresh, outside third party perspective on both of their issues. I don't really know how Velvette will be handed in her season in 4, but what I do know is that it's going a totally different route then both Vox and Val. Both of them had long term baggage from their pasts in Hell.
Meanwhile Velvette so far has seeminly had a BLAST in Hell the same way Alastor once did before Hell ended up giving him that baggage. While Velvette is by far the most level headed of the Vees, and her bringing new ideas and pushing them forward is incredibly important for the Vees, Velvette also needs her own reality check. And Valentino and Vox having their experience and history will be important for Velvette's arc. If both Vox and Val are killed, or even if one of them are dead. Velvette is basically just alone and idk how that would be more interesting in cannon and not just as fannon. (But I am just speculating at this point)
Again, the main thing I'm getting at is killing even of the Vees kinda defeats the entire point of them as a villian trio. And that is something that is better explored in fannon; going route in cannon would suuuck imo. And I'm glad that the main villain getting killed every season is NOT the direction they went, as it would feel like a major pitfall.