I see it more as when the rain falls: who will have the best strategy and the biggest balls.
When it rains, it rains for everyone. So nobody is lucky or unlucky. Unless silly things happen, and we've seen that enough in the dry already.
Well for example one driver can come into the pits on x lap, it suddenly chucks it down on x+2 lap, just in time for the other drive to make his stop. That's good luck.
Wouldn't that be nice!
A driver's championship decided by the driver's ability!
Well I know I just meant rain races can go either way, you can either have everyone equal and we see who is good in the wet or you can have one where certain drivers just get lucky, as above.