I'm pretty sure people that actually decide what will go on the box are from marketing, or advertising, not the actual graphic arts department, so insulting the people who design it is largely unfair. It's like when you (if you work in retail) are told to go stack a product so that it's a cube, or so that it's an inverted pyramid. It's idiotic, possibly unnecessary, but it's what they want, so you do it so that they will give you money.
I think that, possibly, the difference may have to do with American social relations. First - I don't appreciate Americans on a whole being insulted. It happens a lot, I get it, we're all apparently retarded and violent and we love beer or... whatever it is. That said, Americans do tend to be more detached from the people around them than certain other countries (see: Japan) when it comes to the workplace. I don't know about other people's jobs, or people who love their jobs, start companies with friends, etc, but most people are doing the above: doing what their boss tells them to avoid conflict and to get "teh moneiz." You never ask your quest givers why they can't just go find twenty badger eyes for themselves, you just start mowing down badgers to get them.
Some other countries (and this comes from a place of heavy conjecture, so if I sound intelligent, I'm sorry) tend to have more inclusive attitudes towards work. They work /together/. I'm not saying people in other countries love their jobs like no tomorrow, but there are notable differences in the way that some countries raise their kids in mind to work.
This is an extremely long, rambling post, and I've gotten away from the point. Basically, box art in America may suck - and I'm not saying it does every time because, well, I buy off Steam and there is no box involved - because certain larger companies in America don't give a rat's backend what their graphic design team thinks is a bad idea. Marketing says slap a giant floating head on it to grab people's attention, so you slap a giant floating head on it and die a little more inside, go home, drink, and write a webcomic.