I don't really see the relationship between the two ...
It is obvious that the dark iron dwarves will never have the bronzebeard option, which is a basic race, already playable ... the opposite could have happened if the dark irons had not been an allied race.
Dark irons could receive the frostborn option, that would be more interesting, fire and ice together

.
But we will stay on the main subject, the high elves, an option not available for alliance players, which has always had the potential to be a playable race, and / or now with the arrival of shadowlands, to be a customization option.