#2. The Avengers Will Never Help Each Other (Unless It's in an Avengers Movie)
OK, fine, so Spider-Man isn't going to swing into battle against the next big threat to New York City that doesn't exclusively involve him. But how come Steve Rogers didn't immediately call Iron Man in Captain America: The Winter Soldier when S.H.I.E.L.D. turned evil and tried to kill 20 million people?
We know from the endings of The Avengers and Iron Man 3 that Bruce Banner, aka Hulkamania, works in the same freaking building as Tony Stark -- they're probably four floors away from each other at any given moment. You'd think a call to that front desk would be #1 on Captain America's speed dial. Same problem with Thor: The Dark World and Iron Man 3: Wouldn't the rest of the Avengers just kind of show up on their own to an alien invasion on live television or Tony Stark's Malibu estate when it gets demolished by helicopters in the middle of the afternoon?
"Fuck that. I'm not helping him move."
Well, no, because the primary cast of The Avengers has only signed on for six films apiece: three of their own, and three Avengers movies. That leaves precisely zero room for Chris Hemsworth to show up as Thor in an Iron Man movie or for Robert Downey Jr. to come zooming in and render the second half of The Winter Soldier completely unnecessary.
Think about it -- in addition to being maybe the greatest superhero movie ever made, The Avengers simultaneously ruined all future movies involving any of those characters. It's like when you were a kid and only had three of the four Ninja Turtle action figures, so you had to keep pretending Leonardo was on vacation.
#1. The Stories Will Never Resolve
The Amazing Spider-Man 2 is the second Spider-Man 2 we've seen in 10 years. Big deal -- the first Spider-Man trilogy is over, and now we're moving on with the next generation of the character.
Well, let's think back on how that first trilogy ended. Was Spider-Man 3 a satisfying conclusion to that storyline? No, not at all. It ended more or less on a cliffhanger that never got resolved, sort of like the last episode of ALF. Plans for a Spider-Man 4 were scrapped in favor of a total reboot of the series, because apparently all of us had forgotten Peter Parker's origin story and needed to be reminded of it.
"This time he's not bitten by a radioactive k.d. lang."
Meanwhile, the current slate of Marvel Studios films (the ones starring all the different Avengers) are absolutely being developed with the idea that the stories will never end. Unlike Christopher Nolan's Dark Knight trilogy, wherein the story of Bruce Wayne came to an unequivocal conclusion, Tony Stark is just going to keep shape-shifting like a Time Lord as different actors step in to play the part over the coming decades. He's never going to conquer his alcoholism or retire peacefully to some tropical island. He's just going to keep turbo-punching supervillains in his rocket suit until the end of time, and that is completely according to Marvel's plan.
"Please, cruel universe, just let me nail Anne Hathaway in France."
You see, they have a very strict set of guidelines that they impose on each director they hire, which is why (with the exception of Jon Favreau and Joss Whedon) no director has made more than a single movie for Marvel Studios. Marvel is noticeably unwilling to talk about whether they expect Whedon to return for Avengers 3, which kind of makes it seem like they don't have any idea how much time he's going to log into Avengers 2 before he gets sick of their bullshit and goes back to making shows about witty conversations in science fiction universes. Marvel doesn't allow directors to take artistic license with their characters the way Christopher Nolan did with his Batman trilogy.
Meanwhile, Fox is trying its luck with the Fantastic Four again. Their new Fantastic Four reboot hasn't even started filming yet, and they've already set a release date for the sequel. Pretty soon they're going to set a release date for a second Fantastic Four reboot before this reboot even comes out. Meanwhile, Fox is slowly rebooting the X-Men series before our very eyes with Days of Future Past, which combines the original X-Men cast with the new X-Men cast. Days will lead directly into the sequel X-Men Apocalypse, which is set to feature precisely none of the original cast.
20th Century Fox
Not that it's a bad idea in all cases.
All of this adds up to each superhero getting a new series with a new set of actors and directors every few years, leaving a trail of vague, abrupt endings to incomplete stories in their wake. Yes, true believers, the future is a steamy coiled pile of Spider-Man 3's.