I'm very late to the party, and I'm not sure what has been said in this discussion besides Onhell's 10 year old post.
Living in Sweden however, no-one alive has known war. Sure, there was WWII and the Cold War, but Sweden itself hasn't been at war since 1814. Current political issues in Sweden are rising nationalism, high immigration and poor integration causing mistrust against immigrants, education system struggling with falling results and privatisation of schools, healthcare, farmacies leading to poorer service due to being ruled by profits that are then moved out of the country etc. Can't really say that this shows in the music, especially not metal which isn't usually political in the slightest.
But my point is that living in misery isn't the reason for Swedish metal being escapist in nature (a point I do agree with). We're one of the most privilegied countries in the world, based on economics (what financial crisis are you talking about? when? we didn't notice), healthcare, education (you are even paid to study at university level) and equality among many other areas.
On the point of American vs European metal, I tend to be extremely euro-centric when it comes to my music taste. The music I listen to tends to be Swedish, British, German or Finnish, and that's it. I actually can't name one American band that I know the whole discography of. I don't know why that is.