Re: Backwards compatibility
Face it: if Windows always did something well, is exactly to offer an excellent backward compatibility for applications, up to the point that some issue can be easily tracked to the need of letting old software - often written by clueless developers who kept on coding on Windows 2000 and later as it was still Windows 3.1 - keep on working.
You can have some fun reading Raymond Chen's "The Old New Thing" blog and find what applications MS developers have to cope with to let them run even if they are really bad coded, often because in use by the classic "Fortune 500" customer you can't tell "hey, you developed crappy code, rewrite it per our OS specifications, read those at least once every ten years".
I still see developers, often those using some RAD tools, fossilized in very old programming habits dating back to more then twenty years ago, and unable to evolve as the OS does. Dinosaurs Windows still need to support...
Which other OS still supports running *binary* code written more than twenty years ago? Can you run Mac OS9 applications on the latest OS X?
With Linux, you may have issue even recompiling code written a few years ago, because some library APIs changed enough to create troubles... sure, if someone else maintains that software for you, you don't notice, but try to recompile some older application nobody maintains... or worse, run the binaries...
Biting the hand that feeds IT
