It really was not intentional, since I love the 4 of them, i think its just that the sonh choices for Ayu were amazing, while my favourite songs from the others are not in the list (So Nice, Nichiyou no Asa, BLUE, Say The Word, Lollipop...)
For the record guys I'm really not a fan of older music. Like it's the reason I rated so much of Utada and Namie's early singles so low, I really don't like that late-90s/early-00s sound. In fact I only gave like 5 songs from around that time an 8+ I think.