I can't say for sure how many people got one, but as someone who has let their sub lapse, I received a survey from Blizzard about wow and why I wasn't playing, and what things I'd like to see that could bring me back. They had a lot of spots to fill in things in your own words and the those sections specifically asked you to be as detailed as possible. As a non-raiding, non-competitive, casual player, you can be sure I gave them a lot to read.
Whether or not such feedback will amount to anything is anyone's guess though.
I disagree. As someone who would come back with the right changes in design philosophy, I think asking for feedback from me and those like me is a worthwhile endeavor. It's not enough to just try and stop the hemorrhaging of players. They need to at least try to recoup some of those who left.