I’m not even one of the people who thinks Infinity War was a bad movie, I just think they could have done so much more with it with relatively few changes, in ways that frustrate me.
Like if they’d changed Thanos’s motivation just slightly– if they’d framed it as him trying to, essentially, weed the garden of life in the universe so the rest of the plants could grow healthier, rather than just a coin toss- it could have prompted every other character to wrestle with the question of who gets to make the call of who’s worthy of living and who has to die to enable that.
Basically every MCU hero has been actively responsible for, or at least complicit in, destroying locations and individuals they consider the bad guys. Some of these, we as audience are on board with; when you take down Hydra, for example, or the Chitauri, it’s hard to argue. But Thor courted war, and Tony made weapons, and these are things their character arcs have hinged on them moving beyond but that history lingers. Natasha was on the wrong team before Clint recruited her, and Hulk went on rampages. Steve and Sam and Rhodey were all in the US military; even as ‘good guys’ they have blood on their hands.
Thanos’s goal could have triggered introspection, even as they were trying to take him down, in a way that could have recontextualized the entire MCU to date. Where is the line where you can decide who’s allowed to live and die? Where is the line where you can’t be redeemed? Obviously, Thanos is on the wrong side of every answer, but just raising the question could have made the the more personal for virtually every Avenger.