Meh, I'm rambling, but the fact of the matter is this- ALL other tanks, except Guardians, have a instaneous way to greatly increase their EHP. Guardians ONLY have cooldowns for this. Thus, fight mechanics that directly hit EHP, bypassing avoidance, tends to be significantly rougher on Guardians then ALL other tanks, which is why blizzard gave us both 20% extra stamina AND 30 sec CD barkskin for 5.4, AND are letting us keep em so far.
Don't think anyone is really disagrees with that, but it makes more of the case that all this EH for Guardians is necessary versus a niche since our active mitigation has many holes in it. Currently, the only times I've died in raids were pretty much intentional wipes and getting literally one-shot, while our other tanks typically die to more than one hit or more frequently. I do credit the amazing natural EH of Guardians, but I think I'd die more often without FR or if my base EH was similar to other tanks.
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.