My point: It's actually rational to assume FB messages are more valuable, and given people who do that, it's equally rational to send them messages on FB :)
It's not a huge money-making opportunity, but it's the first step towards a path I've been wanting to take for quite some time.
It's not that I'm mining Facebook for jobs any more than I mine my phone for jobs... It's that by boycotting it, I cut off a means of contact that others might prefer. (And I could also appear childish or out-of-touch as well.)
Personally I am just old fashioned in that way, I still run my own email server. I don't feel too happy about my communications belonging to some mega corporation.
Also, I don't like having to log in to FB to get my messages, and in turn to be trackable by all the sites that partner with FB.
That's just my reasons - but I don't boycott it. If somebody messages me on FB, I usually reply. I just don't initiate communication on FB.
I also found a great band called "The 21st Century Monads" because I was looking through famous people's profiles, and it's the only music group on David Chalmers' page.