Legality shouldn't be an issue. As long as the site has the appropriate disclaimers (see
http://www.sjgames.com/general/online_policy.html), it wouldn't be in violation of the online policy -- there's never a problem with posting your own original character to the web!
As for interest, I'd imagine there'd be some, but you'll never know for sure without creating it and seeing. The hard part, I'd imagine, will be quality control -- making sure people upload their characters right and include the right amount of information (whatever that is).
Personally, I have to say that I have no use for it unless every character includes a text blurb -- just one or
maybe two sentences -- that says who they are. Something like "Joan Satchell (TL7 serial killer disguised as a housewife)", where I can get a short taste without having to click on the character to see the whole sheet.