I'd say it's more on the active mitigation side of things (or short cooldown abilities) where Guardians don't have a "temporary EH boost" ability, at least something that's guaranteed on-demand. Warriors and paladins can guarantee an EH boost by blocking, DK's have several tools for physical and magical damage reduction on short CD's, monks have Stagger, Guard, and other talents/mechanics to mitigate physical and magical damage... Guardians eat things in the face and heal up afterwards, but we do have Barkskin on a 1min CD (T&C is random and only prevents what I affectionately call "combo attacks" on us, like Dire Call + Triple Horn + Auto-attack).
However, that is class design, and outside of using a major cooldown to take a hit, our only short-CD ability is Barkskin that temporarily boosts our EH. It's partially why I would actually glyph for Survival Instincts on some encounters, because we do lack a method to raise our EH against periodic attacks that have the ability to wreck a tank. Our armor and T&C help mitigate (pun intended) the occurrence of such issues, but sometimes it's not enough or will not directly address the situations where we need that extra EH. If, by design, we either completely avoid or take full hits, then Guardians should likely have more short-term EH-boosting abilities or just a flat-out boost in EH at all times. Boosting our stamina modifiers is the easiest method of doing so.