I just tweeted this: People who aren't on Facebook make me nervous because there must be something wrong with them.
I used to be annoyed with friends who continue to live without trying Facebook. I realize constantly updating one's status might not be everyone's cup of tea. Yet, in this day and age, not having a profile amounts to not participating in modern life. Being literate in 2011 means knowing what wall postings are and what a Like button is. Of course, knowing how to communicate via social media trumps the ability to write a letter or even make a phone call nowadays. Using Facebook is just a basic skill that's important in order to be a functioning member in today's society.
More annoyingly, trying to keep up with people who aren't on Facebook is hard. It puts an extra strain on any existing relationship having to try 'hither and thither' modes of communication. In simpler terms: Not being on Facebook is plainly and simply rude.