I see MC there aimed at the 480/277 circuits but nothing for 120/208/240 if you want something other than black/white and adding phases from there.
I think this change in 2011 should have exempted 120v circuits at the branch circuit level, perhaps only for switch legs.
It did not change in 2014
I can understand wanting to identify 480/277 circuits but BOY on the line to line and the purple/gray 277 seemed to do a pretty good job. They should have just codified that.
The only confusion with that is if you had 480 wye and a center tapped 240v delta.
I think that would be so rare that it is not an issue tho.
