This is a really, really, really silly debate in the grand scheme of things. Why is Hulk on the team? Why is Hawkeye? Why is Black Widow? Because she can speak latin and he fires arrows? Is it because they are super-limber? Why is Cap? Because he's got a good heart and punches super-hard? Dudes. You have a super genius who builds freaking mech suits that are basically walking atom bombs. You have a thunder God who created tornadoes, and bust through the back of a giant's skull.
You need one of these things to take down an army. Heck, Thor, Iron Man, Captain, and Hulk already DID take down armies in each of their respective flicks.
This "I'm a super-nerd who needs to be proven the imaginary limits of a superhero's capable strength because if I don't get an exact figure I am going to crap myself in a four year old style temper tantrum" debate is probably the most ludicrous complaint anyone could have with the quality of these films. Then again, fans are... "fanatics," so, I guess it's to be expected. I'm also not knocking anyone to be clear, I am just not sure why it should matter. At all.
Still, I do think it is obvious Hulk is going to be the macho man in terms of strength in the flick. He's going to be fighting the entire team, we know this much, and he's not just going to kneel down and take it like a whimpy baby. Did he seem de-powered to some compared to his comic book self? Sure. Was he more grounded? I don't know. He went up against a Captain America knock-off and turned his bones to brittle dust with a swift kick after being provoked. For all we know, ol' Jadejaws could have been holding back with the military (which is all he was given to fight,) and with Abomination being stronger to begin with, Hulk clearly goes from eye-rolls and stumbling around after having his butt handed to him, to an aggressive monster who rips out his opponents bones to use as a make-shift shiv in an attempt to murder him and creates sonic blasts with his hands.
As for a mention on why a thunderclap wouldn't have sent the copter flying/the smash crumbling the roof? ...Did we forget Betty was there? You know, the only object of affection and care for our Mr. Hyde? You think he wants to kill her just to get to A-Bomb?
All of it made sense for the flick. And I liked it, that finale is one of the best in the MCU for me.
It might be more fun to "test" the big guy just like Tony is reportedly doing out of curiosity and see where his limits can go. To back up November Rain slightly, he doesn't make sense to be part of the team.
On the other hand, I believe that for a different reason. He's an uncontrollable liability. Anyone else can hold back, anyone else reacts when they are hurt, they flinch, they stumble--Hulk doesn't. Banner would obviously love the opportunity to belong, but Hulk a is dangerous wild card of to which know one seems to know his limits outside of the opportunity of sedating him (which is likely easier said than done.) And personally, I cannot wait to see where they go with that.
Edit: With the adamantium thing, yes, it's probably covered under Fox's agreement. Not in terms of "THEY OWN THE WORD," but in terms of that word being specifically applied to a unique metal with that name which is impervious. If a movie comes out that takes place in a quarantine where everybody is suffering from "Blood Blackening Virus" (or some such nonsense) that has a specific idea behind it and a second movie comes out with that exact same concept and name... they can, and likely will be sued.
It isn't a matter of "But it's Marvel's baby!" No, they gave this baby away until said baby has had it's full course at another company and is nearly beaten to death before it can return to it's original mother. They take that baby and they are kidnappers. ...This analogy got weird.
There is a reason they went with Vibranium already. Adamantium is more well known among the GA due to the success of the X-films. If you think Marvel wouldn't have capitalized on that for the strange purpose of wanting two super strong unbreakable metals in their continuity, then I don't know what you'll be willing to believe.