DFFOO is very careful to keep characterisation and story elements true to the originals. In order to do that they like to have input from the creators and original production teams to make sure they keep things consistent and don't just make up their own interpretations (this was clarified in another part of the interview). I believe most of the original production staff for Tactics no longer work with SE, which might make it more difficult to craft the character builds and stories they want whilst honouring the original games.

It also explains why they don't do a lot with FFXIV. Since it's an ongoing story they might find it difficult to pin down characters and story elements without causing conflict with the ongoing story (especially now they are moving out of the 'our memories got wiped' plot).