I think people wanted a new epic plot, more superheroes, and villains. The Incredibles was always character first though.
That movie dealt with martial conflicts, job/settling issues, family's being supportive of each other being the best they can be. Syndrome, killing off supers, and the omnidroid stuff was background noise and only interesting in putting that stuff in motion.
This film continues the story of the family, and in that sense I think its a success. Which is where Brad's interest always was, and he says as much. I think where people's expectations differed was they expected a better villain than Syndrome and more superhero business. A classic superhero story - bigger, more epic and creative than the first.
This film was more domestic than that though, more intimate, and more interested in its character arcs that related to the real world, for better or worse.
Sure, I can get that. Though I feel the movie was also a disappointment on the family side of things. It essentially reset a lot of the character development in the first one.
The first one ended with the entire family working together for the first time and embracing the kids as part of the superhero family and the end scene was literally everybody suiting up to battle the Underminer, for the first time as a whole family. Incredibles 2 however opens up with the family once again fractured, because apparently the kids were still regulated to the less important tasks (watching Jack-Jack instead of fighting the Underminer).
Mr. Incredible is still the macho dude who wants to play the hero and he shows this when Bob Odenkirk wants Elastigirl instead of him. Sure he gets something different to do than in the first (looking after the kids), but that plot quickly devolves into another retread of the well known "big, manly man needs to learn to be a family man" (again, something that was already less obviously done in the first one, with him realizing he can't save the world on his own).
Elastigirl literally just mirrors Mr. Incredible's plotline from the first one, saying yes to an offer to become a big hero again and getting lost in it. It's only less well done, there's nothing like the scene in the first one where Mr. Incredible finds the corpses of the Supers that came before him and realizing how irresponsible he's been. Nope, she's just a big hero. Her only "mistake" is figuring out who the real villain is too late.
Violet's plot is literally reused by Tony being brainwashed. In the first movie she wants to be less insecure and ask Tony for a date and in the second one she also wants to be less insecure and ask Tony on a date.
Dash's development is also reused, but less obviously. In the first one he learns to be less off a showoff, but in the second he's still a major showoff who just wants to get the nice car and run around really fast in their huge house.
Then there's Jack-Jack, who is still the funny OP baby, only now the joke is reused twenty times during the movie instead of only one or two times.
