As something of an American (I was born there, that's about as deep as my connection to the US goes. I have no love for it), I will try to answer your questions. The first, and easiest, question to answer is "Why does America hate French videogame developers?". This is easy: they're French. For some bizarre reason (that I have yet to fathom), many Americans detest the French. I'm sure it's partly due to many Americans believing that everyone in France is a stuck-up snob, but also because of their two famous surrenders during both World Wars. Somehow many Americans simply can't forgive them for surrendering like that (cheese-eating surrender monkey is a slur I've heard passed around America against the French). For surrendering the French are seen as weak, and thus something to be ridiculed. This is despite their long history of military accomplishments before World War I, including the successes of Napoleon Bonaparte, the seemingly eternal wars with England throughout the Middle Ages (yeah, okay, there were lots of ups and downs for both sides), and allying with the Americans during the Revolutionary War (without their help, the US wouldn't even exist... and yet Americans ridicule them... quite odd).
As for the US box art being as terrible as it is, I have an idea for why this is so. Americans are, in general, an action oriented people. Americans like brave heroes, tales of danger, gunfights, and insanely massive explosions (which explains much of the success of Michael Bay). Most of the US box are you've linked to shows some kind of action going on, and many of it prominently features some form of weapon (it's even being used in one instance). Most of the Japanese and European box art is subtle. It's also arty, and if there are two things anathema to many Americans they are artiness and subtlety. Art is often seen in the US as a foolish endeavor. It doesn't bring in much (if any) money, it isn't action oriented, and it's often seen as the province of weaklings. Artists get very little respect, writers are scorned (unless they're writing the latest bland, vomit-inducing garbage to be gobbled wholesale by the masses, which helps explain the successes of both Stephanie Meyer and Stephen King), and intellectualism itself is often under attack ("They're an intellectual." is the most damning political attack possible, outside of "They're a Marxist/Communist.", in many areas of the US).
I hope I've answered your questions without rambling on for too long.