Had both. When I was 2WD I never really needed 4WD while towing, but did need it several times while doing other stuff around the house. When I upgraded the truck I went with 4WD. Since then I have needed it several times - Wet grass, steep gravel slopes, camp sites with wet leaves.
I've also used 4WD for things I wouldnt have tried before like pulling another truck out of a hole in my back yard. Although I wouldn't tow on ice, I have also driven my 4WD during icy conditions where i wouldnt have taken a 2WD.
Glad i went with 4WD when I did for the needs I never would have anticipated.