‘Rapunzel’ is a story with many morals. Perhaps one: panic can be deadly in a fire or other home security situation. The genius of this device is that it goes beyond helping you be prepared, and reacts to your own fear-induced instincts.
Specifically, as you grip the bar inside this Red Dot Concept Award-winning device (by Sin Sun Ho), Rapunzel holds onto your wrist. And the last thing anyone is inclined to do is let go when holding on for dear life.
There could be other questions raised, like: what if you lose consciousness on the way down? Realistically, though, there is a fairly small window (no dark-humored pun intended) during which that could happen as you make your way down the side of a building.