First, you need to understand just what exactly a torrent download is. Yes, it is used quite often for illegal downloads of copyrighted material, but it is also a very good protocol for downloading public domain and "copyleft" materials that are of enormous size. I have used torrents to download a DVD image of public domain books from Project Gutenberg (it contained the full text to almost 30,000 public domain books), and a copy of Slackware Linux (GPL license). There is nothing illegal about these at all, and torrents was a much more efficient way to download then an FTP site.
My thoughts on SOPA: It was the right idea, but the wrong way to go about it. The idea was to try to crack down on illegal downloads and protect the property of Americans that produce music, movies, books, software, etc. But it put the burden on many web sites to police themselves, and could have shut them down if they mistakenly didn't catch one item. Although it wasn't the intention to shutdown sites like YouTube and Facebook, it could have been possible.
The bill is on hold right now, trying to drum up more support. Hopefully, they will change the parts that are too drastic, and come up with a more reasonable version of the bill if it gets reintroduced again.