Okay, so. Taunka RPer chiming in here.
I feel like there’s a lot of emphasis on Taunka being added just because they’re aesthetically different and people were a little bit let down with Highmountain simply being Tauren with antlers, but consider:
Taunka have a much more distinct culture to themselves. One more defined by strife and perseverance; They are perhaps the most strong-willed of their kin, proving the ability to wield dominion over the very elements of the harsh and unforgiving land they dwell in. Taunka are stubborn bastards, in other words, refusing to let even nature itself snuff them out. To me, this is their defining quality.
They are more distinct in my view than the Highmountain, and certainly COULD warrant the “AR treatment” with distinct racials, druid forms, etc. Taunka given druidism would toe the line perilously close to the nightmare with this approach and their forms could enjoy a darker flavoring that’s been absent outside of the artifact PvP and Drust forms. Likewise their shamans’ summoned elementals could appear as the more twisted, bound ones seen throughout Cata. Blizzard dodged the question of if Taunka shamans are Dark Shamans by saying “they’re Taunka shamans”, a total non-answer that imo doesn’t close the door on the possibility. A rose by any other name, as they say.
Even with that aside, consider their recent (within the story of WoW) history. They’re a people who in recent years have suffered back to back catastrophes with the Scourge, the Twilight Cults/Dragons, and then a second Scourge outbreak. It is not hard to imagine that they would be pushed to pursue magics and methods that would have been seen as taboo in the past and which their cousins still think are not justified.
That being said, having to go through a lengthy reputation based unlock would probably land them in the bin as an even more under-played niche of the already under-played Tauren races, so simply adding a slew of Taunka appearance options to the catalogs might be more accessible. Having character creation overhauled to a degree and re-thinking Racial abilities, perhaps giving all of these similar races the ability to pick between in a fashion similar to the Zandalari Loa racial, would also help. While it doesn’t make as much sense for a Belf to be able to use a Velf racial, there’s no reason to imagine a Tauren couldn’t use Bull Rush or a Highmountain could use War Stomp. Racial abilities might be a whole subject to put aside for another time, with that in mind.
Personally I’d like something in the middle. A less arduous rep - Say that you only have to get to Honored or MAYBE Revered with a close ally or trading partner like the Tuskarr who then give you a quest that sets you on the path to getting acquainted with the Taunka, and gets you up to speed on their current situation over the course of perhaps ten or twelve quests culminating in an unlock. Something that takes an evening, maybe two, but overall you could do the whole thing within the span of a couple of Resets without strain.