I wanted to make up some “pro” and “cons” lists, but I found out that almost everything I wanted to say is pretty obvious if you ever thought of benefits and disadvantages of using flying mounts.
So there will be only one point here which is “cons”:
Without flying, you suddenly bring back to life all the cool ground mounts that you have forgotten about.
I’m choosing appropriate mounts for different races, and it’s fun! A horse for Backston the Human Warrior, a mechanostrider for Micromantica the Gnome Mage, etc.