Agree 1000000% about this.
I always "hoped for" some sort of allied/sub races. But not as we have them today.
More like extra customization for current races (like, instead of DI dwarves, we got Wildhammer ones (which, kinda, is more logical after all)) - and it would be done in such manner that we have tattoos, extra trinkets, beard styles... etc, etc, etc.....
90% of "allied races" could be done that way (mag'har, hm taurens, di dwarves, lf draenei... etc, etc) and I still do believe that nightfallen should be neutral race, just like pandas are.