So you can click here if you would like the full history of Sanctity Aura. Basically, in BC it was a talent to give 10 percent holy damage (not all damage) to all party, not raid, members, and another talent made it add 3 percent additional full damage (not only holy). The talent was removed in wrath, and the vers version was tried in WOD where all party members (all raid members) got 3 percent vers as long as they were in meleeish range. Legion hit, and it was removed again.
As to why it was removed, there are a lot of reasons. For starters, the devs change from expansion to expansion the overall mindset of how raid buffs should be handled. Does everyone get one? Do only some specs? So sometimes the removal is for a broad policy goal surrounding the game, not because it didn’t work for one spec. With that said, though, it is generally bad design to try to give a spec (not a class) a raid wide buff for 2 reasons. First off, if it translates into enough damage/power, you brute force require that spec in all raid comps. Think about, for example, something like mages right now. Regardless of how good they are, because they have an int buff, a raid would be foolish not to take one at least. Now imagine if that was only frost mages who had the buff? Fire and arcane would probably see the bench a lot more just because of that, even if they parse higher on average.
Now, the second reason is that once you give a spec a raid buff, balancing them becomes a nightmare. A dev has to purposely tune down the spec’s overall power because the spec is making all its teammates stronger. But what if I’m solo? What if I’m in a 5 man party? 10 man? 20 man? The buff can’t scale to all these situations, and then the problem compounds if it is a talent, because then you have to balance all that wonky math against whether i take the talent or not in the first place.
These issues I have listed are why historically you rarely see these sort of buffs implemented in the game at all. I would argue that the reason why the devs tried the vers version in WOD is because vers had just then been added to the game and the devs, somewhat naively, viewed it as a largely tanky, survival stat, so it would not impact dps too much. Legion came along, and the devs did a large overhaul to raid buffs, so the aura got chopped out, but if it had stayed, it would probably have become a bigger issue than it was in WOD.
Did it work in WOD? Well we already know devs didn’t like how raid buffs were pre legion, so the fact that it got chopped out tells you already that it wasn’t valued that highly. I think it was unimportant to the vast majority of the players, but for the high end raiders, it was a nuisance uniquely because it forced range to be in melee for the buff, creating degenerate gameplay. So overall, I’d say it was a wash or worse.