Why cool hot water?

Some of my best ideas occur to me in the shower. And this morning was no exception.

There I was, doing the dance with the taps to get the temperature just right, and I thought to myself: "self, why the hell do you spend good money and waste good energy heating the water to a certain temperature - only to mix it with cold water so that you can use it?"

Why indeed? There had to be a reason. Washing machine? Nope. That has a thermostat and takes in hot/cold water to get to a certain temperature. Dishwasher - nope. That actually heats water to damn near boiling. Shower? Well - that's the problem in the first place - the hot water is too hot to use.

I can't think of a good reason to have the hot water hotter than you can use it, except that it has to be stored hot enough to kill bacteria (120 degrees F). So, I turned the temperature down on the water heater. That's got to be greener and save money hasn't it? I'll post the calculated savings. :)