This one might raise a few pitchforks... I'd like to see very limited mech customizing. In other words you have the stock mechs and that's that. The thing to me that no Mechwarrior/Mechcommander game has ever really captured was what made the clan omnimechs special. In both of the Mechcommander games everything was basically an omnimech. You could just as freely reconfigure your hunchback as you could your timber wolf. If you look at the lore of Battletech a mech that wasn't one of the standard variants, like Yen Lo Wang, was a rare thing to encounter on the battle field and required a great deal of effort to do.
I think the new battletech game on Kickstarter is basically going to be MC3