Actually, when "Fair Lending" first came out, there was some comment and push regarding "Master Bedroom". Clarifications came out that this was not considered disciminatory.
Now, re MBR, there is a significant market differential in my markets if the MBR is upstairs or downstairs. Actually marketed as a positive being downstairs, especially with an aging population. Also, we have a 4 BR home. While we have a MBR, the bath is small and the closet is not a walk-in. We are going to remodel, taking one of the bedrooms into a master closet and enlarging the bath. 4 bedrooms are more excessive now, with the shrinking family size.