Y'know I've always wanted to talk to an expert and find out why such a relatively small country has so many darn regional accents.
I think that's fairly normal. It's true for Austria, too, and used to be for Germany as well. We don't really hone our accents and are supposed to speak standard German in school, though, and I guess that's why accents are now a lot less pronounced than they used to be a few decades ago.
The fact that the US doesn't have as many regional accents might be due to it being a nation of immigrants and relatively young.
I don't really ascribe any malicious intent as far as accents and behavior goes. I just figure a show creator has maybe a minute to get across to the audience that 'This person is from _______.' Unfortunately the easiest way to do that is to fall back on tired old stereotypes.
On the other hand, they sometimes do a great job of getting it right. I felt that supposedly German woman in Waters of Mars really nailed the way many Germans speak English and totally avoided the stereotype. Quite impressive. The German we heard in that message from home was hideous, though. But that's been hit-and-miss on the show, anyway.