Final Fantasy X / X2 HD Remaster was the first Final Fantasy game on PS Vita and It did really well. ^^
Maybe that is the reason why we are seeing a better Square Enix PS Vita support! Will be interesting to follow upcoming Square Enix games on PS Vita (Dragon Quest Builders, Dragon Quest Heroes II, Saga Scarlet Grace...)
Actually a GAF insider said that FFX/X-2 performance on Vita is exactly the reason it gets more support (and he/she said it before Square Enix starts the PSVITA announcements).
Yep, it was definitely a good decision to put FFX/X-2 on Vita. :)