I'm slowly laying to rest my idea of levelling a tank alt, partially because common sense tells me that I just don't have time for an alt to fulfill the most gear-dependant role in the game, but also because I'm coming to realise that the tanking I remember fondly from vanilla WoW just doesn't exist any more.
Vanilla WoW was a less egalitarian, but somehow more PUG-friendly place, than its WotLK incarnation, almost because it lacked all the improvements we have come to take for granted.
Back then there were raiders and non-raiders. Raiders were either raiding or preparing for their next raid - with no limits on consumables, no daily quests and with the trash in Molten Core not dropping money or nice vendor-junk to help offset the cost of repairs raiding was a serious business. Tanks and healers either had to pay for regular respecs to allow them to farm, or had a farming alt.
Non-raiders were who you found in PUGs. Probably they were gearing up and getting their attunements - Molten Core, Onyxia and Black Wing Lair - prior to applying to a raiding guild, or possibly they'd weren't planning to raid but just wanted to gear themselves up as best they could, but either way they were generally more accepting of their fellow PUGers.
Except of course that, unless you were a mage, rogue or one of the few reputable hunters, you'd struggle to find a DPS slot.
But once grouped, players knew they had to work together to overcome the instance, especially the tricker mob pulls in the harder instances.
Nowadays everyone is a raider, to some degree, and with the fantastic emblem gear available everyone runs heroics - while being much more demanding of who they will deign to group with. A leading DK tanking blogger is seen wondering if 31.5k unbuffed health will be enough to get an invite to a group. It's common to see people assembling PUGs and demanding not only the "Epic" gear achievement but also the achievement for completing the instance or raid that the PUG is planning to visit.
And once in an instance, now that all tank classes have AoE threat abilities, the burden of crowd control is placed firmly on the tank's shoulders. If the tank has the ability to get aggro from the entire pull, but not the gear to withstand it, then they are blamed for the group failure. Unless it's the healer who's deemed to be undergeared, in which case they are blamed.
Once they join a PUG, all players seem to forget any crowd control abilities they may have, presumably only to remember them once they step outside again.
I'm not sure if part of the problem is that tanks are afraid to ask for help with crowd control, for fear of being derided. Whatever the cause it seems to be that now, the group mindset that was once quite common even in the worst PUGs of yesteryear, is absent.
And, while adding good emblem loot to heroics may have made them far more popular, it's made them a far less friendly place to be for the tanks and healers they were originally aimed at - those who can beat the normal level 80 instances but aren't yet geared enough for Naxxramas.
Hence I'm tempted to stick solely to my massively overgeared healer, and leave my tank alts firmly parked in the level 67 - 73 range. And try to remember that I have a spell called Hex.