Actually, they can provide that (somewhat publicly responsible) UX by extension without tracking at all. It doesn't sound very "googly" to do so, but who knows, maybe they do... ;)
I don't understand what you mean here. How can aggregate long download stats exist without aggregation?
Kind of like putting a warning sign at the swamp without poking for alligators (or yodas)
The warning is about download frequency of a particular file, not filetype.