Rather than saying our niche is EH, perhaps it's more our ability to self-sustain is better than other tanks? When things go to hell, the Guardian perseveres while the other tanks drop! I hesitate to say that without knowing how FR scaling will change in WoD, since more EH to survive non-burst damage is pointless if healers have to do more work to keep us healed overall... plus that niche could scream tank imbalance.
*edit* - Oops, forgot this is the Bear Hug thread. Anyways, with our inflated EH, Bear Hug would end up doing more damage, but that's something easily adjusted later in the design process. A stun doing damage is nothing new, anyways, as there are many in the game currently.