That's fairly superficial, though -- there are lots of easy ways to make serious mistakes that are devastating if your opponent capitalizes on it.
Dark templar aren't special in that regard -- they just happen to strike at one of the more common mistakes (inadequate detection) and have a sort of 'coolness' factor. They gain a bit of undeserved notoriety because losing because you couldn't defend against dark templar doesn't offer any false hope; a pair of high templar clearing out your supply chain*
is just as much of a loss, but if you don't really understand the economics, you will suffer the illusion that you are still in the game.
*: Assuming, of course, you aren't granted comparable compensation -- e.g. your let opponent psi storm your SCV's because you were focused on (successfully) wiping out his probes with a vulture blitz or have a lethal push walking over an opponent's base