Questioning baseball strategy

It's well known that you take a pitch on a 3-0 count. I have never understood this logic. Odds are, unless you are being pitched around, the next pitch will be fastball down the heart of the plate. Most players don't swing at this pitch because there is a 3-0 count..

I would love to see the real stats on this situation, but here is what I feel usually happens. 3-0 you take a strike, the 3-1 pitch is usually fouled off, because the batter is protecting the plate, which brings to a 3-2 count. when anything can happen.

I thought of this now because Carlos Guillen just whacked a 3-0 pitch to deep center field for a triple, and I think that should happen more often.