Tank stance doesn't need to be traited, but it does need to change.
The individuals who say that there is no true benefit to tank stance are correct, especially when it appears that the non-stanced tanks can weather the damage that comes their way through cooldown usage; Most using the damage reduction gained via tank stance as a singular cooldown for an attack.
The issue that most have with tank stance is the damage penalty, believing that the small percentage of damage that tank stances prevent is not worth the percentage loss in dps.
I do not believe the dps loss should be removed from tank stance, but rather that a non-stanced tank should be more vulnerable. An easy way to do this would be to reduce the defense levels of tank armour.
Doing comparisons from the 310 to 340 ilvl tank armour (the items that have defense ratings), the maiming armour is approximately 70% of the fending armour.
If the defense on the fending armour is reduced to equal the maiming armour, and then the tank stance (instead of reducing incoming damage) increases the defense of the tank (a factor of 42.5% would increase the defense back up to current levels). In addition to a small passive enmity bonus, the +enmity bonuses abilities should only trigger if it is used within tank stance. Doing this would create a situation in the tank stance in which is needed; regardless of any percieved loss in dps.
Some tank abilities would need to be reworked around the naturally reduced armour; but in general, it would create a battle situation in which Tank stance is a necessity to the combat. This would also put slightly more emphsis on active healing from the healer as the tank would be slightly more vulnrable.
This of course isn't an indepth look into every change that would need to be made, but i believe something like this could start to balance the need to be an actual tank (and by slight extension have actual healers) instead of DPS with some off-role skills.