I also hear the basic design called "stingers" from time to time.
A benefit for rock-crawling is that it is very hard to flip over your nose if you have a large bumper that angles out, away from the body. The bumper will (hopefully) catch you before you flip nose over.
You can also do it in the rear. If you have more bumper sticking out and back, like a bee stinger, then it can (hopefully) catch you before you flip over backwards and onto your lid.
For the sand, if you are doing a nose dive it prevents you from digging in and flipping over.
Those are the basic ideas behind them. I really never did like the look myself, and figure my big ass winch bumper sticks out enough to have almost the same effect. ;D