The Economist analyzes Tintin, pegging his lack of fame in the USA on the fact that he is a very European hero, written to conform to a set of cultural norms (and laws) with restrained violence, no sex, and the hero as an overgrown boy scout, constantly doing the right thing.
I think the reason Tintin never was a hit in the USA is much simpler: The setting is seldom the USA, and especially not the USA after the second world war. The only album set in the US, Tintin in America (1932), is a deeply sarcastic portrait of the US during the prohibition years, with Tommy-Gun-toting gangsters and indian reservations being replaced by instant cities 10 minutes after oil is found.
There are rumors of Peter Jackson and Steven Spielberg making Tintin movies. I for one hope they maintain the irony and complicated plots of Tintins golden period from 1934 to 1956, with believable plots (well, there is Destination Moon, but that was fun, too, with Professor Calculus throwing temper tantrums) and interesting characters. Tintin is not an action hero, though he occasionally throws a few punches. The animated movies made of Tintin did not have the slickness and literacy of the books, but if Lord of the Rings is anything to go by, Spielberg and Jackson should be able to follow the books just fine.
As for the wider political analysis of Tintin as a "European hero" because he cannot change larger events – or the musings of his possible homosexuality – I think some people need to lighten up a bit. And stop reading the same albums over and over.