Oh I don't disagree with your analysis, it's just that from a revenue perspective MS really does not NEED to charge $100 to home builders. It's a pittance to their bottom line and would generate some nice karma from the home enthusiast build your own PC crowd.
Yes, my home rig runs Linux, but if I could get Windows for cheap or free I'd load it and use it on occasion when the need appears (some specific game or whatever).
Right now though, between browser and Steam I can't think of WHY I need to shell out $100 for Windows. I'm not a heavy shooter gamer and the longer time goes on the games I do like (Like wasteland 2) are available.