Problem being, that the World of Battletech, the UNIVERSE of Battletech is, at it's core, horribly boring . . a select few get to go out and play war in their gigantic toys from time to time, a few others are there to cater to their needs . . everybody else is no different from you and me today . .
So . . what do you want to play in the MWMMORPG? O.o Clan Elemental? Mechwarrior? ASF-Pilot? Tanker? Dropship-Tech? MechTech? Clan-Scientist? If you play the combat type, what do you do when you do not have a battle to wade into? Sulk? Start one?
No, the CBT-Universe is, sadly, very much not fit to be the setting of an MMO . .
Same with Star-Trek actually . .
WH40K . . now THERE is a Setting for an MMO . .