Partly it's a health thang. Nobody in their right mind wants to spend an extra second breathing what wouldn't pass for an atmosphere on a blatantly poisonous world like Venus or Jupiter.
Partly it's a social thang. You're either isolated, doing your own thang by yourself, or you're part of a larger group, which is either on wheels, or packed in a set of chairs somewhere. Facial contact is too important to trust to pediatrally-oriented groups.
And finally, you just get tired of carrying the stupid bolt cutters necessary to get through all the stupid chain link fences that are always in the way.
Copyright 1995 Miles O'Neal, Austin, TX. All rights reserved. Miles O'Neal <roadkills.r.us@XYZZY.gmail.com> [remove the "XYZZY." to make things work!] c/o RNN / 1705 Oak Forest Dr / Round Rock, TX / 78681-1514