1. They complain about all the legacy code in Windows, but dont seem to mention that companies are the ones that demand it, so why would they make their primary customers angry?
2. Who cares if they demolish builds for redevelopment. Lots of construction guys will have steady work for a while.
Good point. The underlying problem is that since the early days of Windows, business applications have used undocumented features, depended on undocumented behaviors, constructed workarounds for structural flaws and behavioral bugs, etc. As a result, those applications are heavily dependent on old, often broken, code deep in the bowels of the OS.
Microsoft has a many technically competent software engineers, brilliant system designers, and great system architects. But they are all hobbled by having to maintain "back-compatibility" with stuff that never should have been done that way in the first place.
Windows will never escape the damage done to NT in the mid-90's by trying to make it act like Win95. Everything after that just added insult to injury. It's really a shame; it could have been done so much better. Microsoft can never take a deep breath and re-do it from scratch, the way Apple did with the switch to OS X.
Make your bed, lie in it.