I thought of another point.
This brings me to question (some more) the thing guys like to tout: "The more you know, the less you need."
Well, what if you're injured to where you CAN'T use your skills to build that nifty primitive shelter.
I know if I was injured, I'd rather unroll my sleeping bag/bivy under a tarp (even if I couldn't pitch the tarp, I could go "burrito-style") than make a debris hut. My bag+bivy+tarp is 5 pounds I'm willing to carry.
The point there, I believe, is that the more you know the less likely you are to be injured, to need makeshift shelter, to get lost, to need to chop yourself a house in the woods and so on, in the first place. But bad things happen to us mortals, so it's never a bad idea to be prepared. Personally, I won't easily give up my sleeping bag and tent or tarp - unless just to have fun for a night or two at most, living outdoors with minimal to no gear for the change.
If one is well prepared, one is immensely unlikely to ever need a debris hut or such makeshift shelters. With the right clothes, you wouldn't even need that sleeping bag or tent. And if you've got the latter two, you should be pretty comfortable indeed without needing to construct extra shelter. Of course, if you screw up and lose your gear, then it's a little different... so don't screw up.