You sound really bitter about a significant portion of the community wanting or agreeing with the concept of Warlock tanks.
Nice arbitrary information. But guess what? A large portion of the community wants and agrees with wanting nothing to do with the concept of warlock tanks.
What would be more "fun" is an actual tank spec. In fact, it would be thousands of times more fun.
Opinion. I don't find it fun because then that forces people to gear up two different specs if they want to min/max. It also makes it harder to get recruited since good raid guilds typically want people to run at least two specs, if not all three.
They have never said that they don't want Warlocks to tank. They said that it was not in their original plans and that they were surprised by the community uproar.
Yeah, actually they did. When DA first came out everyone was like AWMAWGAWD BLIZZARD IS FINALLY GIVING US WARLOCK TANKS. WHOHOO THIS IS AWE-
And then this happened
Just to make our intent clear, the Glyph of Demon Hunting isn't intended to turn Demonology warlocks into a tanking spec. You won't be able to queue as a tank for Dungeon Finder for instance and won't have the survivability or tools of say a Protection paladin.
Historically, warlocks felt tankier than other casters and could even off-tank some encounters. We have made an effort in Mists to recapture some of that flavor. A warlock with this glyph should feel like they are about as effective tanking as an Arms warrior who pulls out a shield and swaps to Defensive Stance, or a Feral druid who goes into Bear form. You might be able to off-tank adds or pick up an actual boss for a short period of time if the tank goes down.
To make warlocks an actual tank would take more significant changes. For example, we want tanks to have to pick up separate tanking gear than their DPS gear (this is even true of druids) and want tanks to have to give up some of their DPS potential in exchange for their survivability. In short, it needs to be a commitment, and that's the sort of thing that needs larger gameplay changes than just a glyph.
That shouldn't stop the glyph of Demon Hunting from being fun though. As you can probably tell, we are trying to make even the major glyphs more about character customization and fun.
The glyph is really only there for warlocks to go AWMAWGAWD TANK DIED. I'LL SAVE THE DAY. Whether that's actually really all that helpful in a raid is...well I've been in a hardcore raiding guild this tier and we never had something like that happen, so I doubt it's utilized that much.
It was never intended to change the class into a hybrid class, but why would that negate anything?
Changing a pure to hybrid is a big step. People typically play a pure as their main if they don't want to be bothered by learning how to heal, or tank encounters. While they may have to switch to the current best spec they're still doing damage, and they only have to learn/perform a different rotation.
They gave us a half-baked glyph which, because it serves literally no purpose and is a detriment in both PvP and PvE, is underused for the amount of developer time that went into it.
And thus if I had to put money anywhere I bet Blizzard ends up canning the glyph sometime in MoP or at the release of the next expac. I dont' think their design intent of DA is ever going to come to fruition.
Warlock tanks tanked several raid bosses in vanilla, BC, WoTLK, and Cata using both Aff and Demo (Meta or Sl/Sl mode respectively). Much more than Shamans. Don't pretend Warlocks aren't far sturdier than every other non-tank capable class out there, because we are and testing it will prove it to you.
Don't hold onto bias if it's holding the class back.
Most of warlock off-tanking was due to Blizzard creating unique fights that required a non-tank class to "tank" part of an encounter. They weren't true tanks in the sense that they tanked raids if they wanted to. Off the top of my head I can think of the one SSC fight that required a high shadow resist lock, I believe a fight in BWL required a caster tank (not sure if locks just got favored in that or not), and I'm pretty sure Illidan needed a lock tank. WoTLK also had an ICC warlock tank fight. There was also Gruul's lair where mages tanked (and I remember some warlocks tanking it, and succeeding but it was very hard to pull off). That doesn't make mages tanks now though, or put them in any sort of position to argue for it.
And shamans were actually initially designed to be off-tanks (jack of all trades), but the design was scraped in TBC.
What is the value of Pure DPS except in the name, an irrelevant title that holds very little bearing on a classes abilities or unique traits?
Blizzard still says that their concept of the Hybrid tax isn't a hard written in stone concept, but that they want pures to be ahead of hybrids in DPS when you assume equal play. So there is an intent at difference.
As far as you should be concerned, adding a fourth spec would not inhibit on your typical playstyle in any fashion. It will not result in a DPS loss, it will not result in you being forced to tank, it will not result in any of the current specs being changed in any way.
Even Blizzard admits this isn't accurate, and they don't see it that way.