Is the "same old sound" the real reason of Ayu's declining sales?

[EndOfTheWorld]

Up until Party Queen I basically loved everything Ayu did. Her lives, her fashion, and most importantly the music. For me, the number one main issue is the music. Each album since Party Queen seems to have a small handful of memorable songs and the rest just blur together in my memory. I'll be watching a concert sometimes and it will take me a minute to try and remember what song she is singing.
So I don't want the the old Ayu back or the old sound back. But I wish Ayu's music would have the same quality as the older albums. The compositions, arrangements, and production of recent stuff just has nothing interesting going on. This is how the term "typical Ayu" came to be.
I can go back and listen to albums from the past and always enjoy them, I personally find that revisiting the old albums is rewarding. You can go back to those albums again and again. But after one listen of TROUBLE, I felt I had experienced everything it had to offer already. There really isn't a reason to go back to TROUBLE. I actually rarely listen to any albums after Party Queen. Usually just a few select songs from each album that standout and that's it.