It's pretty common knowledge the fact that, currently, Spider-Man does not belong to Marvel Studios. He's at home with Sony Pictures, which keeps his involvement with the likes of Iron Man, Thor, Captain America, the Hulk, and SHIELD off the table. He's a stand-alone hero in his own, stand-alone universe, standing alone next to Gwen Stacy. And he's better that way.
But there are lots of cries for Spider-Man to blast through contractual agreement and join ranks with the super team of the Avengers for their future endeavors. With rumors that OSCORP was supposed to make a cameo in The Avengers film, fan speculation and theory ran wild about how the two universes could intersect, despite the fact that the character would provide for quite the distraction within further Avengers installments.
Allow me to explain. With the reveal of Thanos as a big bad villain, possibly being saved for either Avengers 2 or Guardians of the Galaxy, The Avengers is obviously going to start heading in a galactic direction. Thor 2 is jumping into some more magical elements than the first film decided to cover, Iron Man 3 is going to take the next step with nano-technology, and Captain America: The Winter Soldier is also taking a more modern, "political-thriller" take. While that last one may not seem in line with the others, you have to remember SHIELD's involvement and how they're also heavily involved in the idea of cosmic intervention. And then, of course, GotG couldn't be more galactic if it came bundled in Star Trek wrapping paper. And we can't forget Ant-Man, another Marvel film heavily rumored to have some interaction with how SHIELD plays with the gods of the cosmos.
What's The Amazing Spider-Man hoping to cover? Well, it's got the pressing issue of solving the relationship between Peter's parents and OSCORP and a possible love triangle between Gwen Stacy and Mary Jane. Spider-Man's just not fitting into the big picture, here, folks. What the movie is trying to do is fine for its own universe, because unlike the pictures at Marvel Studios, it doesn't have to come across in layers that are going to be relayed or expounded in other "off-brand" films.
And, honestly, would Spider-Man really be a big help to The Avengers? Practically, no. He's no militant strategist or power-house, and while Parker's smart, he'd be eaten alive if thrown into a room with the likes of Stark, Banner, and Hank Pym. Really, the only dynamic he'd be bringing to the table is one of age. His witticism is already captured through the likes of Iron Man, and his genuine, nerdish, and nice-guy personality can be found in Captain America. Spidey works well on the team in the comics, but in the comics, The Avengers boasts an enormous roster, with a surplus of various heroes. And unlike the rest of the MCU heroes, Parker hasn't exactly come to a full arc (yet) in his movie. He's still incredibly inexperienced.
Let's be honest, here. With Ant Man joining up and rumors abounding that Ms. Marvel might be a possible entry, and characters like Falcon being introduced into the MCU, do we really have room for Spider-Man? He's got his own set of films, whether or not he's joining the Avengers. Wouldn't you like to see some new folks? I know I do. "But what about a cameo?" To that question, I beg, "Is Spider-Man really a character worth splitting down to a cameo in a movie about superheroes?" It's a moment I think we fanboys are playing in our heads a bit too spectacularly. Even if Parker's cameo was one that would save the day for the team, realistically how contrived, unsatisfying, and unwholesome would it come off? The answer: very.
As of right now, Spider-Man does have a place on the Avengers roster or in that universe. It's okay to dream, but don't let things get too out of hand. These are two separate entities, and they'll work better that way.