The best would be if Microsoft makes just one OS and then simply continuesly fix bugs which they find by time and here and there put something new in it.
If they for example decided that XP was going to be the one and that all until today's day they were just fixing the bugs and optimizing it,XP would be one of the best operating systems ever
If you ask me it is better to make one OS and then just continuesly fix the bugs in it as you find them by time rather than making a new one all from the beginning.On that way that OS would be just great.
But I guess Microsoft is making new OS(s) just to make more money instead to make just one OS and simply work JUST ON IT.
I guess that one day when money stops to exist (hopefuly during my lifetime) then people (in this case let's say Microsoft) won't lose so much time to make all from the beginning (which causes many bugs) and instead they will make just one and just work on that single OS in order to make it better and better and better with every service pack and other bug fixes and optimizations.
Cheers!
(And yes I hate money and always did hate it.It just makes this world a worse place then it already is)...