I think what happened is that Ayu lost her fans' trust and love by releasing songs like Born To Be and Beautiful Fighter...I mean come on...those were weird (no offense to those who like the songs)..I actually never finished the whole song...I would just skip it half-way, forcing myself to believe I might like them..
But truly, Secret is soooooooo much better than M(u)...and I don't think it's due to the rock sound of Secret...Duty was her best selling album and it was rocker than Secret...me think that Japan in general has weird taste...