I disagree with you about Windows7 though. I run into windows in Windows7 all the time that can't be resized. It's one of the reasons I hate using Windows.
The 'msconfig' dialog in Windows can't be resized since ages and every time I have to use it its like, hell no, how can the prohibit resizing that window which contains very long file paths.
Disabling window resizing is okay but it should be used carefully and rarely as possible.