Maybe they're doing it wrong, then? Google adds features that fundamentally alter my web-experience all the time, but nobody minds because they either
-package it as a completely separate product with its own url (gmail.com, maps.google.com, etc.) before gradually integrating it into search results and other products.
-make them optional (i.e. Google Instant, Gmail Labs)
-do a test run on a small subset of users (which Facebook does only to test before they scale, seemingly never to determine if the change will piss off users)
In short, maybe continually tweaking core features like Messages, the Timeline, Photos, etc. isn't the only way or even the most effective way they can leverage their almighty graph.
-package it as a completely separate product with its own url (gmail.com, maps.google.com, etc.) before gradually integrating it into search results and other products. -make them optional (i.e. Google Instant, Gmail Labs) -do a test run on a small subset of users (which Facebook does only to test before they scale, seemingly never to determine if the change will piss off users)
In short, maybe continually tweaking core features like Messages, the Timeline, Photos, etc. isn't the only way or even the most effective way they can leverage their almighty graph.