It looks like the preview releases of IE11 work fine. MS Changed a default value between preview and release versions.
I'm going to choose to apply Hanlon's Razor in this situation.
-How often do people who have to do something to detect chrome/firefox version?
Unless you are doing something with bleeding-edge experimental APIs probably, never.
-How often do people have to do something for a specific version of IE?
All the time.
Chrome & Firefox have been mostly compatible for the past 20 major versions. IE has yet to make two consecutive versions compatible with each other.
Also worth noting: Firefox and Chrome support more versions of Windows than Microsoft's past 3 Browser releases have.
Again I don't this is necessarily a distinct case of anybody trying to be evil. This is just a symptom of a bigger problem.
Tweaking Firefox to send the same user-agent string "Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.3; WOW64; Trident/7.0)" causes the exact same problem. It's a Google problem.
ETA: In standards mode, IE sends "Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko".
"Hey, if we make Google uglier, maybe people will use Chrome!"
"Probably, they are used to IE not working"
Not sure who had the slip-up, but evil works both ways :P