I can't use the argument that any of these OS's are 'finished products'. Every one has patches and updates that address central core issues, and I've never seen a Major Version that wasn't treated like Successor's Super-Patch.
I am frankly unsure of what true benefits any Successor OS offers that couldn't have been incorporated in SP_ for the predecessor. WinXP 1.0 had that ridiculous 128Gb partition limit. Of course, so did most motherboards. But it wasn't but a few months before 1.01 rolled out and that was fixed to the 2Gb file-size limit.
Changing the Partition Size and Storage-Address-Limits seems like a major deal. Incorporating a standard SATA driver set seems puny, by comparison, but XP never did that. Vista's cutey-pie aero features made it terrific to look at but obviously was a massive albatross about its neck for those that had to use it. And it suffered from Day One for that. All of its later updates and fixes gave its fans a good OS, but after waiting years after XP was delivered, Microsoft's obviously hurried neediness to shovel that out the door remains a curiousity.
"Why not wait another 9 months? What big bad wolf was huffing and puffing THEN?" There was some line drawn in some sand somewhere, though, and rather than put out a good product, Microsoft delivered a crippled XP 1.0 and a far worse Vista 1.0.
I think XP 1.0 escaped most criticism because it was dovetailing an incredibly slow Win2000, and offered superior upgrades to Win98-SE, a final tombstone over WinME and threw the doors wide open to any company still stuck on NT 4. But it was also an "entirely new" Windows - the registry system which was heralded as the Be All Fix All service of all time. Gag cough cough... yeah... right...
It was better, from Day 1, than all of those for quite a lot of existing equipment as well as all the New Stuff. Heck, even HP's printer drivers worked, too! (Unlike Win2000's first day, or NTs or Win98/95, etc.)