so is Durable a feat tax ...
ducks
There are unique circumstances which made it so for my game.
Firstly, we're running Rise of Tiamat, the playtest version. There are lots of dragons, and dragons hit pretty hard. My buddy and I decided to divvy up the DM'ing duties; we'd each take a handful of the adventures, and then we'd play when the other was running.
My buddy tends to run things very tactically, and won't soften the blow when things are stacked against the PCs. But at the same time, he's not the greatest at communicating everything that's going on. For instance, he won't always give us a sense of just how deadly an encounter we might be running into is, but he also won't give us enough 'recon' to make an educated decision on the matter.
Long story short, we wound up in a TPK at the end of the second adventure. It wasn't even close. Then I ran the third adventure, and that was fine, and then we hit adventure four and nearly TPK'ed again. We lost one PC, but at one point, every single PC was on the verge of death. We had to eke out a victory.
Following those two significant brushes with death, people began to build PCs for durability.