Good skills! I have done down small/gentle flights of stairs on MTB a few times (including ones made of mud held in place with boards on hillwalking trails). I've never done more than about 3/4 on a motorbike though, but I'd love to learn.
There's an entertaining video (which I'll post up if I find it) of one of our local heroes using a freeway overpass as an impromptu 'junction' to change direction on a dual carriageway, instead of riding several miles on to the next turning point. So it can be a useful skill.
I like my bike because I can overtake 4x4s down farm tracks with a week's worth of shopping on the back.