I think the biggest problem is that everyone thinks they're a comedian. You can get away with saying almost anything if you're funny about it, but Daniel Tosh and Michael Richards found out that you better be damn sure you're funny if you're going to talk about issues as sensitive as rape and lynching. Or at least you better be funny about it if you aren't hiding behind the anonymity of a computer screen, which allows you to be a jackass with no repercussions.
Louis CK manages to talk about rape while being funny, but 99% of the people out there do not. Here's Lindy West reading some of the comments that were directed to her after her fairly thoughtful appearance on Totally Biased. Really disgusting stuff.
http://jezebel.com/if-comedy-has-no-...many-511214385