There is a huge difference between things like
rape threats,
'I wish your mother die of cancer',
'if you open you mouth again, I'll find your house and burn it'
things like
"Women have less IQ than men and you are best example of it"
"I could answer you question, but you are too dumb to understand it anyway"
and things like
"I think that all muslim people are terrorists"
"Whoever believes in God is stupid beyond saving"
"Immigrants have 7 less IQ on average and are gaming social benefit system"
There is a difference between personal threat, personal offense and generic not politically correct statement (even if it is wrong). But I have a feeling that all of them fit nicely under broad term of 'hate speech' and while first category is used as a driving point, it is all about shutting up third category - making it illegal to make any generic statement which can offend anybody imaginary world. Of course, people will argue that statement "All muslim people are terrorists" really mean "we should deport/waterboard/kill all muslim immigrants", which can easily fall into first category... but same way you could interpret facebook post "I don't like my math teacher" as "let's buy guns and go Columbine on him"
My personal opinion is that direct, person _threats_ should be punishable/forbidden. But I will defend my right to say to other person that he is stupid because of the things he said, things he believes in and I want to be able to make it generic ("All people believing in homeopathy are dumb").