How nearly every character has become a version of Tony Stark.

I read some review of a guy who watched a marathon of the MCU movies in theaters before Age of Ultron and said it was like watching the same movie 10 times. That's the issue. Each MCU movie is trying to stand on its own but they fall into their own story formula. So you have the same cocky, quippy character over and over because it's a familiar routine.

This isn't a huge issue because movies are all independent of each other. They don't share a universe so you'll naturally see the same archetypes and tropes. But when you do have a shared universe, suddenly your stories start all looking the same.

That's an issue I have with comic universes. A lot of main characters are just slight variations of other main characters. Tall, square jaw, 2% body fat, super strong, same hair style, similar face. You'd probably get the same issue if you had an anime main character team up: spiky hair, big swords, shouting about friendship.

My point is that this is one of the major flaws of a shared universe.