My issue with the BUILD UP for Avengers: Doomsday (and it's not necessarily Doom)
Doomsday has a major issue in terms of build up, which I think most of us can agree is due to the frantic pivot away from Kang. And while Doom's build up is a bit lackluster when compared to Thanos, I don't think it's the main issue like most people assume; the real issue, in my opinion, is the build up with the Avengers themselves, and all of the heroes in general.
The Infinity Saga effectively established each major character in the Avengers roster all the way back in Phase 1, and then continued to add more characters from that point onward. Whether it was Iron Man, Thor, or Captain America, there was a general focused storyline being told in the Infinity Saga before Thanos himself really did anything. And when Endgame happened, nearly every single character or team we had seen up to that point banded together in the climactic finale. This is ultimately where the Multiverse Saga has failed.
While practically every character, relatively speaking, in the Infinity Saga had their stories connect in Infinity War/Endgame, the same cannot be said for the Multiverse Saga. Almost half of the characters who have either been introduced or should've been the lead focus are completely nowhere to be found leading to Doomsday, and that's a huge problem.
Captain Marvel, Doctor Strange, the Eternals, all absent with no clue as to what they're doing. Scarlet Witch is just dead after a somewhat scuffed villain arc. Shang-Chi hasn't even been mentioned in 5 years. Nick Fury and the Skrulls... I don't even want to talk about that. Hulk hasn't been doing squat, so nothing's changed there. I won't even mention the atrocity of She-Hulk. Sam Wilson's Avengers team is practically non-existent still, let's be honest. The Thunderbolts are fine though, but they ain't doing much to Doom aside from Sentry lol.
Here's what I think should have happened to more effectively set up the Avengers/hero teams for a much more effective collaboration:
The Eternals: get rid of it, nothing meaningful happened with them.
Shang-Chi: make a 2nd movie for him.
Captain Marvel: Make an actually good movie that establishes her as more of a leading figurehead for the MCU. Throw in an interaction with Sam Wilson as Captain America: he takes charge of hero activity on earth while she manages the space frontier.
Doctor Strange: if the rumor of him being one of Doom's witches/wizards is true, then we should have gotten a 3rd Strange movie showing how he and Clea eventually encountered him.
Scarlet Witch: while she's dreamwalking through the Multiverse, perhaps she encountered Doom at some point and, finding connection with her over their lost families, Doom would advise her to regain her lost children at any cost.
Captain America: give him 1 or 2 movies where he establishes himself to the world as Steve's successor and slowly organizes a new Avengers team.
Thunderbolts: this was good, no changes.
Fantastic Four: ideally 2 movies before Doomsday, though just having 1 is fine. They feel more like this saga's Guardians of the Galaxy in that they're more distant from the main roster before teaming up in the Avengers movie.
These are some changes that I think would have drastically improved the road leading to Avengers: Doomsday, not just for Doom himself but also for better establishing the newer roster of heroes that face him. What do y'all think?