Did you just discover this? There's nothing new or even Windows 8 specific about it. Users have had Windows downgrade rights for a long time now.
Agree with most of your keen UI observations, especially the one above which bugs the heck out of me. They've tried their best to copy the Windows 8 frame border but not only does it look completely out of place on Windows 7, the worst part is it disobeys Fitts' Law. In Windows (all versions since perhaps 95) the native window frame has a small blank space to the right (and in older versions also the top) of the close button, BUT if the window is maximized one can simply throw the mouse pointer to the top right corner and click there and it will activate the button. Clearly the copycat UI was made by developers who haven't really studied how the original functions. Now an action that should require next to no effort at all (simple closing of the app window) makes me pause every single time and ultimately wastes precious time. (Please don't bother to tell me how there are lots of other ways to close the window. Those have nothing to do with the UI complaint above.)
I'm actually not opposed to CCleaner looking more like a native app on Windows 8, but it should not only follow the same principles on Windows 7 too, it should also function properly with no UI inconsistencies that show carelessness on the part of the developers.
