In Wotlk Death knights were added as a class. In MoP Monks were added, and now in Legion Demon Hunters will be added as a class as well. In addition survival is now a melee spec, and Death Knights (and now Demon Hunters) are classes often played as alts.
By counting the amount of specs:
Ranged:
Frost, Arcane, Fire, Demonology, Affliction, Destruction, Shadow, Marksman, Beast master, Elemental, Balance
Melee:
Fury, Arms, Frost, Unholy, Feral, Sublety, Assassination, Outlaw, Havoc, Survival, Enhancement, Retribution, Wind Walker – Guardian, Protection x2, Vengeance, Brewmaster, Blood
So 11 ranged specs and 13+6 melee specs. Even assuming that there are no one playing a tank spec in PvP there are still more melee and ranged specs.
By counting it differently, but instead assuming that 0% of population would queue up as a tank spec.
Ranged: Mage, Warlock, Priest (1/3), hunter (2/3), Shaman (1/3), Druid (1/3) = 11/3
Melee: Warrior, Death Knight, Monk (1/2), Paladin (1/2), Hunter (1/3), Druid (1/3), Shaman (1/3), Demon Hunter = 5 or 15/3
So assuming that players are chosing a ranged, healing or melee dps spec equally likely there are going to be 36% more melee players than ranged.
This disparity will of course only widen when you consider that classes such as a paladins, rogues (only in PvP), death knights and now demon hunters always have been favored by the masses.
So who is this going to hurt.
Random mass instanced and world PvP have always been working like this:
Ranged/healers ---------------- Melee vs Melee ----------------- Ranged/healers
With melee being more durable and offering stronger peels, it was possible to be on the receiving end of high damage, but prevent enemy melee players from catching on to ranged/healers. Ranged players in turn dealt more damage, but were a lot weaker if they did not abuse their 20-40 yard range advantage.
If melee players went too close to the enemy ranged group, they would get burst down, and they would be out of range of their own healers. In turn ranged players had to time their mobility/CC/defensive cooldowns when they were being targeted by melee players. Smart positioning and kiting until someone helps you have always been the most important skill as a caster.
So where is the problem. Classes/specs such as shadow priests, ele shamans, moonkins, warlocks and to some extent hunters have very little mobility, and have to rely on their small arsenal of instant casts, defensive CDs and CC when being trained by melee. Most of these specs are being pushed out of PvP simply because it is unbearable to play.
It is also very bad design that melee classes have a lot more CC and mobility. This means that absorbs, damage reduction, self healing, and instant casts is the only tool avialable, meaning that you either become unkillable 1v1 (see current affliction warlocks) or that you just want to kill yourself when one melee decides to sit on you.
How often do you see other ranged specs than aff/demo warlocks, mages and the rare hunter or moonkin in BGs? Personally I don't very often. And it's going continue to be like that, especially after testing a lot of the PvP talents on beta.
So if this really is a problem, or if it is just me being ridiculous? One fix to this would bring back some of the CC and damage reduction that a lot of ranged specs previously had?
For example why did shadow priests lose psychic horror and shadow form damage reduction? Why does warlocks have to chose between mortal coil, shadowfury and tankiness, when a hard casting spec like destruction have had all three things since Tbc? Why is elemental and balance survivability toned so much down? I understand the purpose of trying to fix a lot of the shit in PvP MoP brought, when all classes and specs all of sudden had an answer for everything. The problem is that most melee specs kept their mobility and control, whereas ranged specs simply don't have an answer to the most common occurence: Being trained by melee.
I understand that it is different with reliable healing/external defensive CDs/melee peels, but that is going only going to be a thing in 3v3. In 2v2, random and rated BGs, world PvP, duels etc. is going to be a terrible experience.