Guess I'll go against the grain here..
I wouldn't mind seeing cosmetic changes only - hair, or make-up.
I would rather not see major reconstruction surgery available unless you're at lvl 50 and willing to pay CC for it. I have about a thousand screen shots from my pug heroics/flashpoints that i've taken along the way from various characters and would really hate if the same characters i've grouped with are no longer the same race, sex, etc.
EDIT: make choice matter to some degree. Otherwise, what's the point of playing this game?