Ease down on the throttle... Your just grinding metal.
Look, I don't think you can say that the way things were in the comics until recently (say, oh... the last, what? 8 to 10 years?) should have no baring on the films. That's me personally though. Of course there's going to be changes from page to screen. But facts are that Hulk is there at the start of the team and absent for decades at a stretch from the books and there is a reason inherent to the character. As I've pointed out lots of times, Whedon himself says that in his view at the heart of it, the Hulk story is more a werewolf tale than some straight up super hero uplift story. This is not conducive to being part of a super hero team whose mission is the protection of the wider world. It's out of step with the essence of the Hulk character, a half man/half monster hounded at every turn, mistrusted and hunted by forces that want to exploit or destroy him. The Hulk IS Banner's rage and pain as well as his sense of superiority. This is not a team player character. Banner might be, but in the end, the Hulk is too much of a wild card. I think that if it plays out like you said, sort of a rehash of A1 but with a different ending with Bruce leaving, that it makes sense. Banner realizes that he's more detriment than hero and gets outta dodge before people start placing calls to Thunderbolt Ross and Talbot. This also opens up TWO spots on the roster both speaking of the team but also the cast. Screen time dedicated to Hulk and Banner can be distributed to newer characters.There are reasons beyond just "it was in the comics" that make sense for Hulk to leave. When I think of the Hulk, I am sorry to say, but I don't think of Superman in ripped jeans. I think, "Man/Monster" and that's not a combo that could ever make for a stable team member. Add in possible feelings of betrayal, a return of the fear of losing oneself to the monster, apprehension at how the world will react... Yeah. That's not adding up to "everyone shakes hands and has a hearty laugh about this all in Avenger's Tower" right before credits roll. YMMV but that's my view.