So it wasn't the concept that made the movie a hit, but the execution.
It would be a mistake to count out the key factor of the movie as a patriotic, feel-good actioner inspired by 9/11 and the Afghanistan/Iraq wars that a wide swath of Americans could get behind. We Yanks love to reflect our history and struggles on the big screen, but the 9/11 attacks were a painful memory, the overthrow of the Taliban was bogged down by intractable opposition and the fact that Bin Laden had disappeared, and Iraq was big old mess almost from the start. (Heck, it wasn't until 2011's
Transformers 3 and 2012's
The Avengers that blockbusters even started to feel comfortable demolishing American skyscrapers in purely fiction stories again.)
Iron Man gained contemporary relevance from Tony's capture in Afghanistan, and the Ten Rings, while obviously heavily modeled on the Taliban, didn't shout religious slogans or even anti-American rhetoric at all, IIRC, thus effectively muting any potential "problematic" political concerns. And then the main villain turned out to be an American CEO, an apolitical target no one objects to. Moreover, at a time when America had overwhelming technological superiority and firepower in its conflicts overseas, but to no apparent tactical advantage, Marvel provided a fantasy of a high-tech weapon (sorry, "highly advanced prosthesis") that
did effectively and quickly neutralize enemy combatants, while thoughtfully sparing civilians.
Compare the movie to
Green Lantern, in which the hero is a military test/fighter pilot, but aerial dogfights hadn't been a thing since the Korean War, and he never ventured outside the US except for jaunts to space (I think - I never saw it). That movie, in short, also had a "cliched, by-the-numbers origin-story plot," but none of
Iron Man's contemporary relevance. (Nor, for that matter, did any other superhero movie, or even action movie in general, really, until 2013's
Lone Survivor and 2014's
American Sniper.)
In short, I agree that
IM1's cast chemistry and rehearsed zingers was that movie's
biggest draw, but one shouldn't count out the appeal of its core concept.