So, first it was, "Queen stopped being rock," and now it is, "Queen stopped writing good rock." Nice job moving the goal posts there, man.
And the second statement, that they stopped writing good rock, isn't even true.
Funk, dance..eh, that is semantics. But if we want to look at jingle.boy's example of Radio Ga-Ga, Freddie Mercury didn't write that one either.
The Battle of Evermore is a very nice song vocally, but I can think of dozens of Queen songs that are better in that regard.