Previously it was necessary to know what kind of threat you had on different targets, who else was targetting what, what your OT was doing (oh, and remember threat management on fights like Gruul?) as well as planning your pickup on new adds, etc..
Nowadays, you have the same amount of buttons, but there's far less to really think about. Since mobs pretty much stick to you now, it's moving occasionally, taunting occasionally and keeping your AM up.
So, while you may or may not have more buttons to press and "things to do", tanking is a much more introvertive style of play than it used to be. I think that's why tanks who started tanking back in the BC era (I didn't tank in Vanilla, so no real foundation for that) and enjoyed that hectic, heightened awareness type tanking find the new tanking model (i.e. threat is no longer an issue) a little lacking.
Is that a bad thing? Maybe for those who enjoy the hectic type tanking like myself, but for the community as a whole it's probably better how it is now.
- - - Updated - - -
Add management alone would be enough to make the comparison crazy. In TBC it was such an insane chore to pick up more than 1 add, now I basically LOLEAPTCLAP and pick up every mob within a 5 mile radius and they stick to me like ugly starving hookers in January.
I recently got my first tank in nearly 8 years of WoW to 90.
And I'm gonna be honest, I regret it, I'm probably going to go ret for anything but premade groups with friends, and nothing has made me hate other people as much as tanking has. I like tanking. I like the mechanics of it. It's fun, and doing it for friends is pretty cool. But random groups? Never, never, NEVER AGAIN. Between the hunters and warlocks who refuse to take their pet's taunt off, the healers who spam their worst heal while semi-AFK and get mad when you make them work a little (because you should apparently never be running heroics in anything less than full LFR gear, and if you're trying to replace that ONE item that just won't drop, you're supposed to pull a higher ilvl replacement out of your ass or something because god forbid the healer should have to actually, yanno, HEAL), the Derpknights DPSing in blood presence, and the general bitchy "everything is your fault even if it was something stupid I did to get my own stupid self killed" attitude people have? I'm so disgusted with the behavior of random groups that I'm not sure I want to do LFD/LFR for a while at ALL, let alone on my tank.
I used to think tanks were a bunch of jerkass primadonnas.
Then I rolled one.
Now I know why they act that way.
Paladin tanks are even easier, I just spam my shield of righteousness for that 40% damage reduction and wait 3 seconds if I just used it and got a proc. MAN SIGNIFICANTLY MORE COMPLEX.
To be brutally honest i dislike tanking in LFR due to the limited amount i can afk.
I don't want to live on this planet anymore.
That's Blizzard repeating what tanks say when asked.
Tanks certainly SAY that's why they aren't tanking LFR. Whether or not this is actually true and representative of all tanks is another matter.
Personally I've had a blast tanking and if anything I've had fewer shitty experiences than when I was DPS.
I am very nice to any tank I find who is exceptional at their job and class, because those tanks tend to be very rare.. But if you're an idiot, I'm going to call you out as such.
Also, from my experience, the tank is usually the aggressor. More so when they aren't very skilled..
I only have a problem with mouthy tanks that think they are a gift to WoW, and tanks that just pull whenever the hell they feel like it.
Biting the hand that feeds!
I suggested it a long time ago and I am not sure if they have changed it but one thing I would have done was let people select a loot type that is different from their present spec. I know the whole loot system is different now but that was a big problem with tanks in the past.