In the second well of eternity novel, the demon soul, there is a description of eredar warlocks flying using magic alongside the doom guards, so why can’t spellcaster players do so without a mount? Just because it would be unfair towards other classes? It’s an RPG after all, there should be differences between classes, no need to balance everything.
The game would be much better if it would stop focusing on PvP and actually have some versatility and allowing different gameplay and not just 3 roles, which would also make it easier to add more classes or sub-classes, for example going back to the book about the night elves, priestess of the moon could be a sub-class for a priest or a mage, even if those are just slight changes, class/race synergies would add more to replayability.
Also in that matter, could make less global quests whose sole purpose is to waste time so that people would spend more time and thus subscribe for longer