I've always tried to use the correct terms for things. But I'm also a great believer in letting language evolve. If most people think that disinterested and uninterested mean the same thing, then at a certain point - it just does. That's how English works.
By the same token, if so many people use the word vagina when they mean vulva, maybe I should just give up and use that? At a certain point, that IS what it will mean.
Also, in the endless threads about what generally agreed nickname to give the vulva, I've never seen anyone say they actually use the word which is used on MN - fanjo. Even tho that's what thousands of people on this website understand. At what point would that become a default word in society?