Maybe because in this game tanking is so boring and nobody wants to do it so it's always on demand. It's essentially a dps with higher hp but not the same dps numbers. And people in games do prefer to do the dps rather than support/tank in general, which is why there aren't any "need" in queues (except alliance raids and occasionally trials)
Other mmos at least tanks do feel like tanks, interrupting skills do matter, avoidance is important and managing cooldowns are important and it's not just "press 1 button for 20 seconds of less damage".
As for stuff like tank anxiety: I do have Generalized Anxiety Disorder and I tanked in many many MANY mmos, including "the worst mmorpg ever", TERA, SWTOR, and probably others that I forgot, and this was never an issue to me so on this regard I cannot comment.