Tank Stances, Traited

[frostmagemari]

It's more complicated than that. The main point is not that tanks can survive without the tank stance, but that, by staying in tank stance, they reduce their DPS, thus, the overall raid DPS, for a surplus of mitigation that don't really impact healing requirements.
The idea behind a stronger tank stance is mainly to create a larger gap between healing a DPS-stance tank or a tank-stance tank, to the point that what DPS the tank loses is compensated by what DPS the healers can afford.

And you could also increase enemy damage so that keeping a tank alive in tank stance would stlll not be trivial.

The problem with your idea Reynhart, is that to make damage consistently dangerous to a tank that is getting -50% damage, you are making everything absolutely DEADLY to everyone else who would get near an attack from that same boss.
This is a horrible way to balance the tanks, and to encourage tank stances...