This always bothered me too. Both when computers were expensive to me and now cheap. I get paid a good amount of money during the day to use a computer to compute things, display/interface with me, to communicate to humans and other computers. Then my computer is idle/sleep when I am not there. This feels inherently wrong to me. How is that I cannot come up with something useful for my computer to do when I am not there to make real contributions when I resume work? (disclaimer, engineer who programs but not a computer scientist)