What's wrong with avex?

It makes sense. The Japanese music scene was generally always made up of fleeting idol singers. They were hot for a while, then faded out. 3 albums sounds too early for a greatest hits album, but when the artist doesn't last much longer than that...

I don't know if Avex expected Ayu to last much longer than your average idol, and they probably wanted to cash in on her one last time for certain. Ayu definitely didn't want to die out after only 3 albums, so probably saw the pressure for a hits album as a lack of faith in her to make a lasting cultural impact. I don't think they were trying to end her career, but wanted to be sure they could get as much money from her as possible before it did end.