A lot depends on where you live. When I visit Texas or Southern Cal or Florida, I see lots of 2wd trucks. Where I live (Idaho) there are essentially none outside of a few out of area travelers and some contractor type rigs.
Buy a new 2wd truck in the northwest, and I'm not joking at all, and you'd lose more value once you drove it off the lot than you would have spent on the 4wd option just because it's a 2wd truck. They are total dogs to sell around here. My point being that in a lot of parts of the country buying a 2wd truck is a dumb financial choice. In other parts of the country I'm sure 4wd trucks are the poor financial choice.