I perform some of my songs - my style as a performer is rather limited, whereas my style as a songwriter is more varied. I don't want to disservice any song of mine by performing it badly, so that's why i don't perform them all myself.

For me, performing and songwriting are two different art forms - sure, you can be good at both but being bad (or not so good) at one doesn't mean you can't do the other, eg singers need songwriters and vice versa.

Actually, i wrote a post about this on my blog dedicated to songwriting and music recording - i'm not sure if the forum rules allow me to put a link to my own website in a post so i wont, but if you click on the link in my signature, the post is dated from 27th November.