As a person who has leveled all ten classes to 80, tanked with all possible tank classes and healed with all possible healing classes, and had a feral tank as a main...
Tanking is just so much more work than healing or DPS.
So much more is on your shoulders.
The blame is automatically directed to you.
You're expected to know every single thing about an instance before even stepping foot into it.
You're expected to be the leader.
You're expected to make many decisions, even in PuGs, that you may not know the answer to yourself.
You're expected to be constantly aware of every little thing that's going on at all times. One minor slip is much, much more noticeable if it's the tank's mistake.
And I leveled tanking, too, and dealing with newbies as a tank and team leader is just infuriating at times.
Besides, leveling DPS is faster solo.
And easier.
And people are lazy and want easy roles.
Tanking is just so much more work than healing or DPS.
So much more is on your shoulders.
The blame is automatically directed to you.
You're expected to know every single thing about an instance before even stepping foot into it.
You're expected to be the leader.
You're expected to make many decisions, even in PuGs, that you may not know the answer to yourself.
You're expected to be constantly aware of every little thing that's going on at all times. One minor slip is much, much more noticeable if it's the tank's mistake.
And I leveled tanking, too, and dealing with newbies as a tank and team leader is just infuriating at times.
Besides, leveling DPS is faster solo.
And easier.
And people are lazy and want easy roles.