It goes both ways. Just as much as these laws protect the perpetrator, if we go too far in the other direction, we're censoring legitimate speech. These people are horribly abusing the right to free speech, but they're still expressing their belief (i.e. god hates gays and we are being punished for it). I know their belief is fucked, you know their belief is fucked, but at the end of the day if we judged who's beliefs were legitimate and who's beliefs are bullshit, eventually we're gonna be wrong.
I'd much rather let people protest funerals and go on Nazi marches, than start down this slippery slope where we decide which speech is okay and which speech isn't. It's the price we pay for freedom. Even the views that we disagree with are essential for democratic discourse. The theory about the "marketplace of ideas" basically says that a free exchange of ideas is the best way to improve public policy, and anytime we drive an opinion underground, its just going to fester and get more ugly.
http://en.wikipedia.org/wiki/Marketplace_of_ideas
People like the Westboro Baptist Church would do a lot more damage if they were censored and operated underground and only discussed their fucked up ideas amongst themselves. By letting them speak publicly, we're opening up a debate.
I'm all for a time/place/manner restriction at funerals the way we have them at an abortion clinic. I just think that the way our free speech laws are, nothing good will come out of giving politicians the discretion to decide which speech is okay and which speech isn't.