Master does have roots in subjugation. The "master" bedroom was the master of the house and the servants lived in the other rooms and servant quarters. Even if it's only one percent of the population that is offended by it, it's value judgement. Consider the following sides.
How many people are offended by the term "Master bedroom": 1% of the population
How many people are actually attached to the phrase "Master bedroom" and will have any negative quality of life impact if it's changed: 0% of the population.
There is no reason not to rename it. If you care about this you need to find hobbies.