Off hand, I can't think of a reason to renumber neighborhoods unless you want to change the order in which they show up in the main screen.
(Yeah, the remnant of the link had some stuff about your session ID embedded in it, so it would for work you but not for anyone else. I just had to strip it back to the number of the thread. That's an artifact if ipBoard. On the vBulletin that we use here and on Insim, all that same information gets transmitted via cookies.)