Admittedly in recent years I think they've been short-changing customers. Vista's performance issues should have been addressed (mainly wrt boot times), Win7 should have USB 3.0 natively, Vista ought to have had TRIM IMO, the list probably goes on.
I think MS is copying Apple's "just upgrade" strategy, but the difference is that a MacOS upgrade costs about a third of the cheapest Windows upgrade licence.
I think they've changed their tactics in recent years, because for example I don't think that Windows XP would have got any IPv6 support under the current regime (though that may have been due to the long Vista release delay).
Yup 🙂