The problem with those danger zones is that you break the style of play. If you teach players that in every semi-serious encounter, they should burn all their spellslots and dailies then that's what they're going to do in those danger zones too. And then it gets weird, because suddenly they're supposed to play differently.
But the vastly easier recourse is to play as normal and backtrack out of the danger zone, which makes the rest restriction a grindy nuisance more than anything. This problem isn't one with weak modern gamers or whatever, it's one with the game offering one set of instructions and then being inconsistent, and of course with rest mechanics being very generous.
