I would love to see a B12 HellMOO. As long as you could get mature enough players to admin it, with multiple people playing checks and balances for each other, and a knowledgeable coder to patch things up and add new content, then it could work.
It is the freedom to pretty much do whatever you want that gives its main draw to the world of HellMOO. Once you take that freedom away, it becomes a carebear game, and isn't really the same anymore. I do remember when Hell was originally good, but then took a nosedive. The lack of population on HellMOO and HATEMOO wouldn't be a problem; you just offer something that the other two don't have or used to have, and create the nostalgia of past days without the retarded admin or arbitrary rules.
HellMOO is a vicious place, and it should stay that way without admin interference (unless it gets to a really bad point, but even NDY was killable, as seen by the time he died and had his airship broken into by myself et al). It rewards players for becoming stronger, but nobody is completely invincible, especially if people team up, which doesn't happen often due to the nature of the game. I suppose in FPS terms, it reminds me a lot of DayZ, where it is unforgiving, people die and can lose everything, but you stand to gain a lot of enjoyment because it's so brutal and rewarding in a way.
I miss the game it used to be.