I have to admit that I played the FF games because of the name and what it included inside: walk then chocobo then boat then airship (and open world). Changing these modes of transportation means changing FF to me and it will lose what attracted me at first.
Conclusion, I'm for chocobo only but customable ones (pieces of armor/colors/size). I thought about people saying it should evolve and expand but it simply doesn't work for me after all these years of knowing and enjoying what to expect in a FF game.