Brewmasters are scares. Even less represented then Guardians!
Monks are actually really strong when maxed to an optimal level, but under representation stems from a few avenues.
Windwalker Monk has some of the best AOE dps in the game, but lacks utility for the raid, so is under represented.
Mistweaver packed INCREDIBLY potential in MSV and ToT, but then they nerfed Revival massively after buffing all other 3m throughput CDs (tranq, hymn, healing tide) This puts Mistweaver in a very specific niche, where they bring a good amount of dps to the table, and great passive healing, but otherwise they are inferior when it matters most.
Brewmaster faced the same fate, but still comes out on top. They were doing more DPS than the actual DPS specs in the first tier, and most Dogs and Elegon kills had their BrM quite a few percent ahead. Because of this, they too were nerfed, received a flat percentage damage decrease - the first of its kind. The DPS number is literally red, as if you had rez sickness or something. They are still strong tanks especially given their damage even after the nerfs, but are pretty difficult to play when compared to any other tank spec.
What you may not know is their utter dominance in Challenge Modes. They easily do as much AOE dps as the actual DPS players even with the nerfs, and basically have 3 cheat deaths in the form of a backwards roll when things get heavy. They are by far the best option for pushing for a crazy time, but Blood DKs do fit the actual tank role a bit better and their blood shield scaling with vengeance is even crazier than Guard.
unfortunately, all three specs are ever further under represented because of the difficulty each playstyle presents. WWM is probably the easiest to adjust to, but very few people would consider them better than the melee that were previously in the game so its only likely to see some one switch from outside the meta role to try their hand.
MW and BrM are both entirely different play styles than their counterparts, and because of this, its often confusing to learn. Even a player like myself who fancies himself competent at each healing spec just can't get into Mistweaver. The thought of having to attack a boss and heal at the same time is just not why I am interested in Healing.
I play my Monk as BrM in challenge modes very often though, and can say even after all this time it is still tough to master. Its hard to find the right balance of life and death and when to use what resources and how to stay alive, especially in the first few globals as the healer sets up.
