"Users spend most of their time on other sites. This means that users prefer your site to work the same way as all the other sites they already know."
Facebook is as vanilla-standard as it gets.
A similar thing happened when Last.fm did their huge redesign. The new website was all js now, and they quit all support on the forums, messaging, pretty much all the old ways of communication between users. And for me, that was awful, since i was a part of a music collective that communicated primarily on those forums. After that everybody dispersed.
So outrage at a redesign is not always unfounded or silly. Web companies tend to hide things in them.
Most of the outrage I remember was around hiding and removing functionality: Chronological newsfeed, page customizations, network pages, etc