She's still been recording for 10 years and that's truly something to celebrate. Especially watching her grow as an artist from her Avex days to now.
But I think the main reasons she is celebrating 10 years but not acknowledging her career as "Arashiro Beni"are
1. She already had a best album with avex, so I don't think she would rerelease music from a different label on this best.
2. We don't know the legal situation, she might not have any ownership of her old music. Perhaps she would have to pay up to even acknowledge those records or perform them or rerecord them.
I don't believe that Beni would completely ignore her avex releases simply out of disdain. She still wrote and helped create the majority of them after all.
I do think it would be really wonderful if there was a disc 3 that included a new EP of 4 or 5 tracks to hint at the new direction she is going with her music. I'd also love rerecorded music or ~part 2~/spiritual predecessors to certain avex songs just to show how things have come full circle.
Kind of like how DOUBLE had songs like Bed-Part2 and Sweet Time again (which were jazzier renditions of her classics). Or Crystal Kay releasing acoustic versions of Eternal Memories, Hard To Say etc.
It'd even be cool if she sampled or referenced some of her early early material in new records (again Crystal Kay comes to mind when she sampled Motherland in the song Fly To You, or Utada Hikaru's uso mitai na i love + hikari).