1WD has proven sufficient for the modest offroad or off pavement trail riding that I do, with reverse enough to get me out of bad spots, and with a knobbie installed in the rear position (if I have the forethought to do that).
That said, if I had a 2WD machine, I would likely make it a point to seek out situations where it would be necessary to use it and I would enjoy it simply because it's cool. For my riding, it is not a necessity.
"You wouldn't be riding a motorcycle if you weren't an optimist."
- Matthew Crawford
2005 Ural Tourist, 2000 Kawasaki W650