Via reddit: http://www.reddit.com/r/IAmA/comments/2tf804/i_am_hajime_tabata_the_director_of_final_fantasy/
[–]HajimeTabata[S] 90 points 1 day ago
I wanted everyone to be able to play the game on a large high-definition screen. Honestly, my eyesight’s getting worse, so it’s getting difficult to see things on a smaller screen. I’ve seen some questions about why Type-0 isn’t being released on the Vita while X/X-2 HD saw a Vita release. The reason is that the X/X-2 HD Remaster was developed on a PS3/Xbox 360 environment, while Type-0 HD was developed on a PS4/Xbox One environment. So there is a great difference in the technical specs and it would not be easy to export the data to the Vita. As for a sequel, I would love to work on one if Type-0 HD does well.
Well... There you have it guys. Blame his eyes, and the PS4/Xbone.