By that i mean most don't reveal that they have a two wheel drive because the sharks start belittling you and ripping you and your ride apart. I can venture a few guesses why but whats the point? The FACT is, a properly built 2wd can go to 9 out of 10 of the same places that a 4x4 can go. I've seen 2wd rigs outperform 4x4s a few times as well. However to achieve this there is a formula that you have to follow.
Ground clearance + correct tires (correctly inflated or deflated) Locking rear diff + correct wheel-speed + driver experience/knowledge= Fun
Advantage of 2wd over 4wd are well worth it to me. Lower initial cost, fewer parts to inspect/maintain/repair, better fuel efficiency. To me this means that over the length of ownership i will experience less trouble and cost than a similar 4x4.