I don't think niggardly is a word worth popularizing more, and I can certainly see someone (probably someone that is bothered by "loose" vs "lose") using it for

I don't think niggardly is a word worth popularizing more, and I can certainly see someone (probably someone that is bothered by "loose" vs "lose") using it for kicks. But that's mostly because, as you point out, it's quite archaic. I agree with your hypothesis with respect to master/slave, in fact. In this case the word master has nothing to do with slavery though. An equivalent to removing "master" from git is removing Spanish names of colors from crayons to avoid having "black" and... "the n-word" written next to each other.