Why Iron Man? He didn't have power thrust upon him like Spiderman or come from a dark background like Batman. Rather Tony Stark was the ultimate engineer. He developed Iron Man out of necessity and and then out of obsession keeps tinkering with the suit, upgrading and adding new features. Happily the movie left off the roller skates from the early years of the comic books.
Stark has his faults. In the comics, back in the 80's, he spent several issues overcoming an alcohol addiction (while he friend Jim Rhodes donned the suit). But in issue #200, he put himself back in the suit to fight to the end the villain Obadiah Stane in his own suit as Iron Monger.
The movie doesn't follow the alcholism theme but does have Stark as a weapons manufacturer, a womanizer and a huge ego. The battle at the end is still quite familiar.
When I gave up comics in grad school, Iron Man was the hardest to drop. In the movie Stark spends more time building the suit than using it. That's the way a super hero should be.