Except it's not that simple. When Ma Bell was around and people didn't like the monopoly, should they have quit using telephones? Boycotting a service like the telephone (at the time) was simply too socially, and probably economically, damaging.
We have a similar, albeit less serious, issue here. When everyone you know, including family, uses Facebook to communicate and stay in touch, how can you just stop using it? Especially since your own action is utterly inconsequential to Facebook management, while being absolutely consequential to your own personal life.
Internet technology is fast approaching common infrastructure. This would be like 150 years ago, people saying "If you don't like the water company, just dig your own well!"
Of course, these examples are considered "extreme" because sites like Facebook are so new. But this line of reasoning only serves to magnify the real issue: the Internet has had such a profound effect on society that a newbie to traditional industry like Facebook can become so crucial to everyday life in just a few years. (Granted, the word "crucial" is somewhat strong, but we're talking about social interaction, not life or death.)
I can understand the position Facebook has taken. As a private company, they have the right to do as they please to a certain extent. But when a company like Facebook can achieve the same kind of social utility in a matter of years as a phone or electric company that took decades, the law simply cannot keep up.