OMG I must put my opinion on this...muhahaha
To the OP, I can agree with you 50/50. It's true that Ayu's music isn't as SPAZ-INDUCING EPIC as it once was (Once you make something like I am... you really can't top it!) but she's one of the few artists in the WORLD that is consistent in making good music. I've listened to virtually every one of her songs and I can say one thing about her, she progresses. Sure she has a slump but what artist doesn't? I've literally had to force myself to listen to MOON because it sounded so recycled (even the lyrics to a certain degree).
But I can't agree with you on the post MY STORY- (m)u era being bland and uninspired. GUILTY, imo, is one of strongest albums vocally and lyrically; NEXT LEVEL was pure fun and it wasn't super serious and it was cool; RnRC was good but moderate compared to previous works. But her PVs during 07-10...EPIC at least 95% were excellent (excluding You were and the sunrise/sunset vids uggghh)