I'm one of those "if it ain't a 4X4, it ain't a real truck" people; but then I do use my truck for way more than just towing; like getting around in the snow, or getting to the top of mountains on dirt trails maybe 2' wider than the truck. So, my perspective may be a little skewed.

I will say, I have had to use 4WD once or twice in the paddock at Summit - back in the grassy areas in the woods, or back near working camping it can get pretty slick after a rain. But in general if I were buying a truck only for towing I probably wouldn't worry about 4WD. I would just avoid those areas where I might get stuck.