Nomura was juggling too many projects it seems.

I imagine they got fairly far into it before they decided to switch to next-gen. The architecture of the PS4/One is a lot different to the dev kits for PS3/360 so there was probably a very stalled period where the switch over was occurring which likely meant assets had to be built from the ground up again.

A lot of things also happened during the time Versus XIII > XV was in development, like XIV 1.0 tanking etc which likely probably caused a lot of stock to be taken in regards to where XV stood.

Tabata came in, and the 2 year period of him as co-director was probably a transition period where the project was being handed off to Tabata before officially announcing him as director.

Just stinks of bad project management all around. There are likely multiple parties to blame for this.