I actually think this scene is CRUCIAL for A) continuity and B) to show that Loki and Thor, despite “moving forward,” have also REGRESSED to their ORIGINAL relationship dynamic, but in this case, in a good way.
A) Continuity: It was very strange to suddenly lose Jane Foster when the last time Thor appeared, in Age of Ultron, he was bragging about how wonderful she was to Tony Stark, who was similarly bragging about Pepper Potts. And even more considering that the entire conflict of The Dark World was about an infinity gem (the Aether) being absorbed into Jane’s body, and Thor and Loki going on a quest to exorcise it from her. Moreover saving Jane’s life–twice in a single scene–was an act of knee-jerk altruism on Loki’s part which set the tone for Thor forgiving Loki for what happened in Thor 1 and Avengers Assemble. Thor watched that happen, and in turn saved Loki’s life, and later fiercely grieved him, in part out of gratitude over Jane. Therefore showing Loki remembering Jane and remembering Thor’s love for Jane, and recognizing that this is one more loss that Thor has to suffer– reaching out to comfort Thor–is a way of economically tying the Ragnarok film back to The Dark World, which aired way back in 2013. It was a much needed reference, because the rest of Ragnarok is so disjunctively different from the other Thor films.
B) Loki and Thor’s relationship dynamic: Loki was always Thor’s right-hand man and the guy who approached him–and was safe to do so given Thor’s violent temper–first. Loki was always the one who used calm gentle reason to talk Thor down from folly and to lift his spirits. This is shown more than once in Thor 1 and in The Dark World. In Thor 1, it’s shown when Loki comforts Thor about Odin denying Thor his coronation (albeit in part Loki’s own doing, but then again, Thor really wasn’t ready) particularly in the extended scene, it’s shown in the deleted scene when Thor is nervous BEFORE his coronation and Loki tells jokes to calm him down, and it’s shown in Jotunheim in front of Laufey.
In The Dark World, it’s shown with greater poignancy–as if Loki literally CANNOT HELP but be a source of levity and comfort to Thor, because he’s done it all his life–when Thor says “[Frigga] wouldn’t want us to fight,” and Loki returns, with a soft little smile, “well she wouldn’t exactly be shocked.”
Thor is IMMEDIATELY placated–realizes that he is placated–and very sadly returns, “I wish I could trust you,” effectively mourning their lifelong bond.
In Ragnarok, this bond is revived in both the above scene, and, among other times, at the end of the movie (“It suits you”/ “I’m here” ).
And I think that’s beautiful. People think Loki does nothing but double cross and run away from Thor. People joke about how loki “stabs Thor to show affection.” But at his core Loki exists to be Thor’s solace, a habit he cannot fully kick even when they are at each other’s throats. Even in Avengers Assemble, he weeps at having to decline Thor’s offer at peace:
Tl;dr Loki adores his big brother. Always has.
