They are or were currently the most underpreforming class/specs in the game. Their limited range as both a healer and dps is costing them greatly but even their dps and hps is not good.
A little out of combat fun/flavor is not going to break the game.
I would be willing to bet $100 dollars that 95% of people complaining would be willing to trade the increased speed for indefinite up time in normal flying areas and the same uptime as dragonriding in the Dragon Isles.
I would be willing to $1000 dollars that 95% of people complaining would not say a peep about existing flying mounts being brought up to our Soar speed if it meant we could fly like those mounts.
It is not about Dracthyr being better or faster. It is about just being able to fly like the other classes without being on a mount.