The thing about Star Trek is everybody looks good. Imagine if you designated a sex suburb in your city and then imagine who would be walking around the sex suburb. Probably wouldn't be as enticing as Risa..
Risan Customs Agents probably enforce a "no fat people allowed" rule there. If they really wanted to express a message of diversity or acceptance they'd have a girl like Rosanne Barr being led off by some Risan stud.