I didn't used to tap, and didn't feel the lack of it particularly, but since I've been playing with friends and got generally better at playing & singing my feet have just taken it upon themselves to tap & keep time. Its most bizarre when I'm not expecting it. Mind you I have weird feet anyway, and they go round and round in circles when I'm happy (much like a cat pugging its feet when it purrs) - it drives Mark mad if I happen to feel happy and contented when he is trying to sleep!
I think tapping definitely keeps me in time better, and makes me less likely to speed up if I'm nervous.

Kris