Legrope on Board? - definitely a french pervert!

Leg ropes provide some risk.
Losing your board provides some risk.
You always have to balance them out. If I am doing a long downwinder past rocks/cliffs, I figure if I lost my board, a body drag for a long distance in those situations is a lot more dangerous than the chance of being hit by a board.
I sometimetimes use my board leash, sometimes I don't. It was really handy today in some very light shifty breezes. If I lost my board and put my kite in the water, it would have taken ages to relaunch, and no more board. In light winds, there is very low risk associated with a leash. Once the wind picked up, off came the leash.
But for all that, I agree - you're better off learning to boady drag. But I still recommend a retractable board leash for use in select situations. I leave it permanently attached to my harness.