I think context matters. In a real estate context, "master" has always meant "main" or "primary". No subjugation is intended, nor implied. On the other hand, all cars have Master Cylinders and Slave Cylinders in their braking systems. And guess what....the slave cylinder does indeed serve the master; although it could also fit within the context of "primary" and "secondary." So I'd say that braking terminology is potentially more offensive than bedroom terminology, unless a home has "slave" bedrooms.
And maybe the term "master" offends 1% of the population. But someone is always offended by something, at some time. You can't please everyone 100% of the time. It's a noble ideal, perhaps even aspirational, but not realistic. Our Bill of Rights guarantees numerous freedoms in this country (although they are not guaranteed equally, IMO), but there is no "right to not be offended." Maybe it's my white privilege ignorance, but shouldn't we be focusing on reformative ACTIONS, not words? I'm glad we're re-examining EVERYTHING, but it feels like we're "knee-jerk" reacting to whitewash our language, when its our behavior and outlooks that should be re-examined. JMO...