Mayhaps those particular examples were the special reward mounts hinted as a possibility for those who subscribe through 2.0, but it's been made pretty clear that Yoshi-P was keen on the idea of having varied mounts available beyond that as well. So although the giant gobbue godzilla'ing around the grounds is something only a handful of people will have post 2.0, it doesn't mean that other imaginative things will also be racing around.
It's basically that idea of anything but a chocobo as a possbility of a ridden transport kinda turns people off, especially if it will become excessive.