You can't just materialize anywhere in the Metaverse, like Captain Kirk beaming down from on high. This would be confusing and irritating to the people around you. It would break the metaphor. Materializing out of nowhere (or vanishing back into Reality) is considered to be a private function best done in the confines of your own House. Most avatars nowadays are anatomically correct, and naked as a babe when they are first created, so in any case, you have to make yourself decent before you emerge onto the Street. Unless you're something intrinsically indecent and you don't care.