User blog comment:Mark4518/X-Men’ Producer Would Love An ‘Avengers’ Movie Crossover/@comment-1895174-20130219133851/@comment-1895174-20130221065741

Captain America's problems of being in the future?

Aside from a few jokes, wasn't really addressed.

Nick Fury's necessity to be in control of everything?

Aside from his two or three encounters with the Global Security Council, wasn't really addressed.

Bruce Banner feeling out-of-place?

That's not an arc as much as it is a characteristic.

Thor's feeling responsible for what his brother has done?

He didn't.

Loki's delusions of glory?

Again, that's more of a characteristic than it is a personal story.

Thor and Hawkeye had a little less to do for the plot, which worked out great.

Still shows how he was barely able to handle it.

They had plenty of screen time and enough character development.

They had neither of those things.

 Iron Man was not the only character with an arc

He was.

There's not really the time to stretch out such a crossover over multiple films since these things cannot be produced indefinitely and Disney and Sony have made their plans for their franchises in the near future pretty clear (none of which involves the other). He was barely able to handle the large cast for The Avengers, so there's no way a crossover between two large franchises could work well.

And as for the comparison to the Lord of the Rings movies, I could just point to the countless reviews of The Hobbit that criticized the film for not developing its large cast.