You know, people getting perma mounts means reducing demand after a while, espeically with little to no new players incoming. And that equals loss of potential income. It is extremly logical when you shift your thinking to their income based view.
More so when people start crying for perma mounts even if it is more expensive. Then they can swoop in like good guys and grant your wishes.
What's next? maybe skins? We already had some time limited versions through events.