Same unit, members in same (maybe unique) colors? I see the point and it would be fun. (Look at my avatar. It's painted in the colours of the 3rd Tamar Jaegers.)
But: MW:LL is dependant on manual aiming and optical target acquisition. (Like every other 1st person action game)
As soon as you take changeable colours out of the box you will have people complaining about things like visibility, camouflage and fairplay.
That will after many threads and posts (or is it threats and punches? - sry my Bavarian English) result in one of two things:
a) Everybody will - depending on the map - choose certain colour settings, that hide him best. That means, all mechs on the field will look the same.
or b) (and that is in my eyes the better solution) Official games will have to be played in official colours. To underline it: I think right NOW we have these official colours. And that means, all mechs on the field will look the same.
CU Mek