Movies With Large Casts
I don’t think the cast size was the problem. There are movies that have a large cast of important characters who still get character development over a series of films and each have their moments to shine.
One of these is The Fast and Furious Franchise that has a cast of about eight primary characters and while you might say that Tyrese’s character has always been the joke factor, he still has his moments of shine and uses his typecasting to play a significant part across the last couple of movies. Even I have to admit that Fast Five and Furious Six were over the top and lots of fun.
Another would be Marvel’s The Avengers. Every single character had their moment. Even Hawkeye who was controlled for most of the movie still has his moment and his character’s working relationship with Natasha Romanov is explored. You can tell he isn’t needed, but you can also tell that duty makes him do what needs to be done even if he only plays a small role.
Outside of the Fast and Furious Franchise and The Avenger’s, there’s also Civil War. We have been introduced to these characters over a number of movies so it feels fluid as they work together and it doesn’t seem rushed (even if certain plot elements weren’t really necessary). Even the new character of Black Panther didn’t feel tacked on and I’d even say he was the only person who had a really legitimate reason to fight.
The issue I see with Apocalypse is the cramping. They were bent on resolving the conflict in one movie when it could have played out over two or even three movies. The X-Men Franchise was the first to have a large cast of major characters and they’ve pulled it off time and time again including the beautifully awesome X-Men Days of Future Past. With this however, while it started out well, I don’t think they knew how to make the characters organically get to where they needed to be and so they just jammed them up together and gave them flimsy reasons all in the name of motivation hoping we wouldn’t see how forced and overly convenient it all felt.
The primary issue with Marvel’s The Avengers: Age of Ultron stemmed from Ultron himself. He (it?)felt very wonky! He was comedic and playful and wasn’t the dark and serious villain that we know from the animations and the comics. I’d actually expected to see him through more movies and maybe even team up with The Avengers to fight Thanos when he realizes that there is an even bigger threat out there. Call it wishful thinking but I truly believed in his evolution (sort of how the Brainiac of the future is good as compared to his present iteration being a megalomaniac).
Another flaw with Age of Ultron was the fact that the movie was a setup for a number of other movies. From Thor: Ragnarok to Civil War to The Avengers: Infinity War to Ant-Man. The large cast wasn’t the defining problem.
I know I went a bit overboard with my explanation and thoughts but I hope that you’ll humour me. I believe that a large cast is actually a good thing and that a good director knows how to handle them. Final thoughts, see The Italian Job and the Ocean’s Eleven Series.