If Traveller were to be made into a MMOG I, in my humble opinion, should be focused far more on players being able to make just about any starting character they wanted and on a set of detailed and consistant worlds that allowed maximum interaction in various ways. After all, if you were to have say, 100,000 players in a 24/7 game and no two characters exactly alike doing everything from starting and fighting interplanetary wars to trying to just make an honest buck running a freighter, that would be traveller! You would get one character (unless you paid in for more) pretty much to your specs much like say, WoW or Perfect World but with skills already preset along with age etc. You then play until you die. No resurrection unless you want to pay for it. Sort of like Hardcore in Blizzard's Diablo games.
I would nearly let players almost pick and choose what they wanted for a character. Since MMOs are often free with add ons for profit, the way I see one of these for Traveller is that you can get almost any first character you wanted but, that character is subject to a permanent death within the game. You could spend cash to lavishly outfit your character, or have more than one for a price. This would avoid players using quasi-legal sites to get around the rules and do it anyway. Why buy stuff from a questionable virus ridden site when you can get everything allowed right off in the game for a price.
If that sounds unfair, it probably is. But, Traveller is a huge universe and you can always get unlucky. An expensive character could be pricy to resurrect. After all, the people running such a game do have to make a living too.....
But, the game would require the details of worlds, systems and, interaction of players that was consistant. That is, if you go back to a world it is the same as last time sans any changes consistant with the game. The planets would have to move around their stars, multi-ship combat would have to be possible. There would have to be lots of NPCs including very powerful government forces that could reign in players that tried to take over the game. That way you could become a small freighter captain bent on making a profit. Another player could become a pirate preying on you. Yet another a mercenary looking for a fight. For a true MMO Traveller the adventures must be only limited by imagination and your character that you chose and must live and die by.
You would want something where someone could play casually and like it or, could play to chat with friends and enjoy the game without alot of conflict and violence or, someone could be teetering on the edge of life continiously or, they could simply be a criminal and life the crazy life. It would and should all be possible. That is what makes Traveller Traveller.