Bulwark being paired with rampart proves my point. It's not a stand alone cooldown for single hits. You paired it with rampart for the very reason that it isn't 100% reliable ad when it fails the only reason you don't die is because you have rampart up with it.

As for magic damage, it's not exactly rare. Akh morn, triple flare breaths, brand swaps (if you have tanks do it), ALL of ramuh, every attack from Levis head (even auto attacks are magic). I'm sure there's other stuff out there. All this content was new and hard at some point and killed tanks, and I'm sure it's not the last well see of it.

Those 2 reasons is why I always have a big asterisk next to bulwark. It's a great ability, but depending on the situation it scales anywhere from most epic move next to hallowed to utterly useless. It's just a very situational ability. That doesn't make it bad, but it does mean it needs context.