The problem is that healers and dps get on your nerves when you play tank. They all know everything better and start to critize you, especially if you do something else as they are used to.
"Tank the boss over here". "Pull Adds over there" "I have aggro, why do I have aggro?! Aggro everything at one." "Do this, do that." "Complain, bla, bla"

If you play tank these days you need to have a thick fur and as sad as it is, you need to be in the mindset: "I decicde know how this Dungeon / Raid is played, and the rest has to shut up and follow."
And actually that is your role. Lead the party. So if the healers and dps would accept this more and give tanks a bit more space to play in their own style, the role of a tank would be more enjoyable.

So in the end, if the rest adapts more to the pace, speed and playstyle of the tank(s), we would have more people playing tanks. Think a bout it.

PS: I play healer main.