First off, try this trick:
Second, it's ok to nose dive, it can still be recovered, I'd try and practice the technique when you feel comfortable.
Third, when they do happen, having the nose under water helps avoid mast collision with the board. It's usually a good idea to hang on and possibly avoid opening the sail so the mast goes downwind of the board.
Winging there's no pivot around the mast and no pressure on the mast which causes increased momentum in windsurfing.
As an example it's easy to do a fast forward loop in windsurfing, it's a bit similar to pole vaulting while there's no pole winging!