Pop culture. Sure. Kids grow up listening to American rap without understanding shit, they only really interiorize that you need to drop "nigger" and "fuck" every two words to be cool. They believe it's just slang. If they saw a black American they'd try to approach him using "nigger" thinking they're just being friendly. People use "nigger" trying to immitate what they listen to in music and watch on TV.
We don't study American history at school more than we do Chinese or Russian. Heck, most people struggle trying to remember anything at all about our own. And no swear word will ever have the same impact when it doesn't belong to your own language. More than that, most people will struggle to understand just how loaded just one word can be.
To put it another way, your average European racist isn't as knowledgeable as to go straight to "nigger" when trying to think of a racist slur in English.
These are just the facts, and I know they may be shocking, but don't shoot the messenger. It's just how it is. Not defending anything.