You are crazy if you think a good allied race compensate a bad one, or even two bad ones.
Each race is a character template. Each needs to have its own qualities, not rely on the quality of others.
"Void elves are horrible, but it's okay, I feel like playing one because dark irons are awesome."
No logic. It doesn't matter how cool dark irons are if what you are evaluating are void elves and lightforged draenei.
And the best developed allied race is actually the nightborne, btw. Most effort put into an introduction ever.