IF Vanadiel had magic spells that could change your racial origins, then A) NPC's such as Star Sybil could turn into a galka, this would devalue her current existence as the person she is. I personally like the game NPC's the way they are, and the permanence of their existance over many years, this would be devalued if the world had power to transform into other races overnight and entirely change the NPC in question. And more importantly, B) orcs goblins etc. could change to humes etc., travel to Jeuno and kill all the citizens there without having to storm the city first. That would COMPLETELY kill the WOTG storyline instantly, as the story revolves around this whole defending all the cities from beastmen. If beastmen could change race magically, WOTG story would cease to exist, everyone in your home nation would be dead because armies of Orcs disguised as Elvaans etc. would just lay waste to everything from the inside, all NPC citizens in the whole of Vanadiel would live in constant terror because the person standing next to them could be a Troll who changed into a taru magically. As you know, beastmen have very powerful magic already, so in your hypothesis they would also have the change race magic too.