You're saying that people shouldn't need to worry about using their TV in the correct manner i.e. switch the thing off when not in use. That is ridiculous - whether or not the source remains running (PC, Sky box on pause etc.) - a TV provides you with a massive indication that it is on and burning a whole ton of energy when not being used, as it produces an image
Actually no, depending on the usage case it's neither ridiculous nor necessarily producing a noticeable image. For example, in my usage case with the screen saver on XBMC set to "Dim" and the percentage far down at a glance it can look like the TV is off when it's actually still on, just at a very low brightness level. If I were to accidentally go out and leave the TV on like this and XBMC were to crash (which it does sometimes) it would go back to a full brightness desktop with the sharpness cranked up, where it could easily sit for six or more hours. Not good for an LCD TV, even worse for a plasma.
You've also forgotten usage cases where the device hooked up to the TV produces a static image when not in use and no-one will notice regardless of how bright the image is - when they've fallen asleep in front of it and forgotten to set the sleep timers.
So you see, what's obvious to you is not necessarily obvious to everyone else with a TV, and it wouldn't take much to sear images into a plasma panel by accident. Just saying.