It's not that they designed for 6% of their users, it's just that a large portion of the users don't like the change for some reason -- some is the fact that there was any change at all, and the rest are probably real design issues.
I think facebook's main problem is that they could gradually make changes, piece by piece and no one would ever really notice. Yet they change the entire home page and you get reactions like this because the feel is drastically different.