A lot of people dont like to play Tank -

[Fingerhut]

Not even that. Seeing the Doton doesn't mean you can keep the mobs inside. The more you pull the more do the mobs shove each other around, if you take a single step the whole mob group runs around.
There are effects you have to dodge and/or have to move slightly because the mobs are so big and you want to keep the agro from all of them.

In my experience it is mostly the people that never play tanks who complain the most.

Tanking is mostly about responsibility. You have to lead the group (by going in first and "shotcalling"/marking ) and do everything to please everyone else and therefore the group. You have to position the mob right, you have to use your defensive skills, you need to pay more attention to the fight than anyonse else (a dead healer is bad but can often be resed and a dead dd can just be resed) and then doing as much damage as possible with consideration of the former things.
That's what many people dislike about tanking, the "burden of responsibility" (sounds a bit dramatic but you get it ).

But also often tanking a boss is indeed easier than damaging/healing. Many mechanics don't even target you. Sometimes a tank buster you can avoid/reduce by using defense skills but most of the mechanics on bosses target the other people behinde the mob. You normaly don't have to touch stuff or have to place an AoE right and so on.