[Melon Panda]

Utada Hikaru is known for relatively outstanding album sales. The thing about her compilation album is that physical sales of albums were already on quite a decline by that particular year, so while she couldn't match the sales of her studio albums (like anything could top First Love at this point), she did well compared to other artists in the market, thus matching her reputation.

I would hate it if Utada Hikaru released an album a year. It works for Ayumi because Ayumi is just special like that, but for Utada Hikaru, time is needed to create good final product. Plus, her music style evolves with each album, and she needs time for that too.