The tricky part for the producer is, how to make things more difficult for Ironman, since Tony Stark is a genius, and his machines are practically omnipotent. If saving the world is effortless, what thrill is there for the audience? The whole showdown could be over in a jiffy. Any action movie worth its ticket price is obliged to elicit collective gasps of horror and accelerate our heartbeats.
The solution turns out to be quite straightforward though - pry the man out of the suit and make him fight like, well, a man instead of a war machine. As Stark says, he is Ironman, whether he is wearing the suit or not. The man has to put in copious amounts of sweat and blood instead of hiding behind metal, or as he admits, his "cocoon".
There were a curiously number of opportunities for the ordinary folks to participate in the great mission, so that it is not the singular achievement of an elite superhero. For once, the mere mortals aren't just screaming victims or gawking passers-by. Every man-in-the-street has something to contribute towards defeating the villians and no effort is too insignificant to matter. Is this an indication of the current political mood worldwide, some sort of Occupy War Street concession? I guess, even a superhero shouldn't have a monopoly in preventing Armageddon.