And in 1.20b we'll have...

[Elexia]

And yet I've heard few, if any, complaints about materia being added in the exact same way.

Probably because people were too busy complaining about the fact Materia overpowers raid gear, which is a bigger problem than storytelling.

You have yet to properly explain why Chocobos can't be wild when that has been a well established trope in Final Fantasy and why it's completely unacceptable, in light of that, that you can't have a tamed Gobbue as a mount.
Or can I just count that as you don't have a good explanation for that and just hate it because it's a new idea in a Final Fantasy?

See, now you're just arguing for the sake of it since you were the one that brought up the whole "Chocobos can be wild creatures/enemies."