The spheres of Nature and Magic are diametrically opposed in the world of Thera. Not necessarily that they hate each other or whatever, but they are opposites. Like Shadow/Light, War/Peace, and so on. My one battle rager was a wood-elf to try and acentuate that counterbalance, but I deleted early as always.

Wood-elves diverged from elves because they decided to focus more on nature than the arcane. High elves the opposite.

That's not to say there can't/shouldn't be wood-elf mages. That's just the reason there aren't any naturally choosable wood-elf mages.