It is very easy to sway people by giving them the extremes. The other day I had a man trying to get me to join an anti-porn rally, the only problem is, his idea of porn would include my artwork! Including that little faerie I have as my avatar!
The first amendment is there to protect us, but many people only look at extremes. You wave around some horribly graphic, and offinsive image, get a bunch of people insensed at the thought of their children seeing this, then get some laws pushed through. Sadly, everyone has a different opinion of what is acceptable, so many things get censored and wiped out.