Ya'll need to chill have a Kit Kat and just slaughter innocent monsters and claim the money that spawns whenever you kill one, it'll make you feel better. :L
On a more serious note though, I think that everyone's entitled to their own opinions and values, so if a certain player decides to create an account such as WHITEpower, then leave them be, WHITEpower could be a reference to anything and not necessarily the reference that you're thinking of.
Player names like the ones you stated above would not be politically correct and appropriate in a public and real life society, however, this is the internet and people really do say what they think on here so just let them be, its only offensive if you perceive it as offensive, remember, nothing has meaning except the meaning you give it.