I do not believe Facebook should be banned. I'm not quite sure why someone would want to ban Facebook, it's dying on it's own right before our eyes. I personally don't care for Facebook, but I don't see an inherent problem with it that would justify it being banned for some reason.
No, I do not think that Facebook should be banned since it is so popular. If people want to waste their time on Facebook and not be productive members of society then I think that they have the right to do so. Facebook is a form of entertainment and banning it would lead to bad precedence.
Facebook is such a great tool to connect and keep in contact with friends, families, co-workers, or anyone else that you feel like keeping in contact with. Also, it allows you to even play games on their site, many which are very popular. I do not use facebook, personally, but even I believe it is such a great tool to learn and connect with people.