[Spivak]

Also because plugging in faulty devices into outlets is something that ought to be safe. Because with probability 1 it will happen in every house. If the way the house is wired makes the only safe action to shut everything off that's the problem and shitty wiring.

[midoridensha]

Exactly: it's just like computer OSes. You should be able to run a faulty program that divides by zero or dereferences a null pointer without the whole computer crashing. The computer should flag the error, tell you what went wrong and why, and let you continue with your work and the other stuff going on in other windows.

Fault-tolerance is an important and useful thing.