I mentioned it somewhere before: they have the highest spell power, they have chains, they have Arcane Wave, they have immunity piercing, they are the best at dealing massive chaos damage. Giving them Darkness is overkill. Giving them Leto is difficult. And not so much difficult as wasteful. You'll wistfully look at the 20 power, but they'll only use it for stronger upgrades, Unholy Word, slow duration, etc.

+1 initiative for the Orcs? Give me the formula (I love formulas)... In any case, magic already exists. And that plays a role.

A horde of gremlins is certainly great, but the gremlins are so insignificant and weak that it doesn't really matter.