But that's what makes it work. The energy is required. Just because it doesn't use the energy in some cool mechanical way doesn't mean it's being wasted. If you look at it as a black box, then it's a perfectly reasonable expense.

You could look at a space heater and say: wow, it just wastes all this electricity, deliberately causing resistive elements to heat up. Well, of course, the heat is intended. With bitcoins, the extra calculations are a part of what makes everything work.