small things I would have done to make stranger things better (these are not all new takes nor hot takes):
kill off hopper in s3- this would have had his character actually serve a purpose and serve a consequence. would have given joyce some independence and also strengthened her bond with jane
never make mileven romantic - jane deserved to experience the world without romance at the forefront. her and mike could have been a wonderful friendship
actually have vecna kill max in season 4 - would have raised the stakes of season 5 and given lucas some real character growth. could have strengthened the friendship between dustin and lucas, and created and interesting dynamic in the group. would have left room for lucas to have a storyline about his trauma/growth as a character and made him more complex
not bring kali back or make her a reoccurring character - whatever they did to her was just bad. having her in one episode of season two, showing jane that she can be independent and grow from the trauma of the lab, just to bring her back later on, strip her of her autonomy, kill all her found family, and let her be abused til she died (also making her a catalyst for jane’s suicide). her death/recapture didn’t really raise the stakes either because nobody has an emotional attachment to kali. if they made her reoccurring since season two maybe her death would have had an impact.
pair the party up romantically via lumax, byler, and henderhop - if all three of those relationships were developed gradually and realistically, it would’ve been very satisfying
take out the vecna and 12 kids storyline - zero substance since nobody give a fuck about these characters who were granted 30 hours of screen time in the very last season of the show.
replace holly’s s5 storyline with mike - could have been interesting to see mike and max’s dynamic (if max was still alive) and would have given him a chance to workout his depression and internalized homophobia (who said that??)
also obviously not make the traumatized girl kill herself cause it’s “the only option” and uh not made the traumatized boy believe he doesn’t deserve love - just not good writing choices imo