Well, they are your parents and its their house, and you have to obey their rules. So, um, tough. When you are grown up, have your own place, set your own rules. And lets see in 20 years how you parent your own kids....
I know what you are saying. I was a kid once too. My mum stopped me doing all sorts of things. Apparently, that is parenting.
Also, you miss understand my point. I am not saying the government can say what should be allowed or not. I am saying there should be a base level filter that parent can use if wanted.
If the government start telling me, an adult, what I can and cannot see, I'd be very much against that. All I am saying is make it possible for parents to chose. As I said, I would chose to NOT filter.