Never enough, tsa, never enough.
Seriously, though, I'm not sure I can answer to what extent AG's (or any review's) feedback is instrumental in creating change. A lot of our criticism is done in fairly broad brush strokes, anyway, so they aren't necessarily things that can be "fixed" so much as simply done better in future.
When I do speak to developers about design issues, often it seems like we're identifying things they've already targeted themselves. It's not unusual for dev comments to go something like, "We agree with you about Point X being a weak area, but we were limited by Factor Y, or we were trying to accomplish Goal Z in this game. Next time we hope to..." That sort of thing. So yeah, they listen, but I doubt it's often (if ever) anything so overt as "Oh, we didn't realize that failing until AG's review!" (Which is probably a good thing.)
On the other hand, it drives me nuts to see the same easily-avoidable mistakes made game after game.
