Dude, the reason why people "generalyze" men, whites and other opressive groups is because there is history behind it. It's not based on prejudices as how black, latinos, women, asians, gays, etc. are.
I don't arbitrarly decide anything. I'm totally aware of the counter examples. Do you think I would be friend with whites or men if it weren't like that? Am I really saying "all"? Or am I stablishing what the history tells us about it?
So because there is a history behind it, it's ok to generalize certain groups today? History is just that,
history. Just as it is unethical for blacks, women, gays, etc. to be prejudiced against, it is equally unethical to lump past happenings on the backs of the people that live today, just because they happen to share the same skin color of the people that did terrible things back then. The world isn't the same as it was 250 years ago, you shouldn't base your arguments on assertions that claim it is.