I don't know..I mean, seriously,when you crash in a game,do you really continue driving with limited capacity 'till the end of the race?
Sure, initially it's fun to see crumpled fenders and bonnets coming off, but after a while, it starts to get old if that's your sole reason for wanting damage.
Unless you are really 'hardcore', I bet most people press restart or in some cases rewind, and start again.
This is one big reason, for me anyway, why I don't really care if damage is implemented or not, even if it is part of racing.