Heuu cruiseoveride... no.
XP (NT 5.1) was based on Windows 2000 (NT5), which was based on Windows NT4, and based on Windows NT. Back-then the Internet concept as we know today didn't exists and security was Microsoft least concerns.
Windows XP was sooo bad security wise that Microsoft had to stop Longhorn development and put everyone together to make all the fixes for Windows XP so that it holds together and not have businesses and individual drop XP and switch to Linux. This was a critical moment from Microsoft. This made Longhorn first big delay, and made the release of XP SP2 instead. Remember that Longhorn is a new OS... a new kernel, a new system started from scratch, that had to be superior of Windows XP in many ways, and support all the millions of hardware configurations out there. And technology has no pause button... it goes on and faster each day. Making Microsoft do the big decision of dropping support for old technology... hence the reason why many people has problems with the OS.
Another issue, is that Microsoft realized that Longhorn UI was too fancy for CPU's... as the UI was all done on the CPU back then. Also, the OS had many many issues with computers in the sense of lack of performance. This made Microsoft restart the Shell system of Windows, which added more delays. However, brought GPU rendered UI in Vista and even more under Windows 7.
Another added delay was that Longhorn was available in 64-bit. Back then 64-bit CPU was not widely used. Many still had P4's... and AMD 64-bit was still expensive (Intel didn't have a desktop oriented 64-bit CPU (I mean a real 64-bit CPU)).This made Microsoft simply wait.. they did improvements but no development at full speed as it was before..
Then Microsoft decided to make the bold decision of quickly patch up a 32-bit version of the OS due to pressure among shareholders and investors in the company to release something... FAST. And that is why we got Windows NT6.0 (which is miss leading as it's actually a new core... it should be New NT 1.0 (or New New Technology 1.0)) but that was that, and that made chip makers think it's an upgarde version of XP, and not focus on their drivers, until Vista was out and they got blasted with angry customers. And add Microsoft bad decisions after that moment like: lack of documentation for IT's to adapt XP setup to Vista and not the same registry hacks (if any) which could brake the OS, focus the selling of the 32-bit last minute ultra buggy Vista, instead of the well done 64-bit counterpart), bad/lack of marketing, lack of informing companies to about Vista new Core, and well the rest..
You didn't buy Vista for the feature... the point of Vista was a new core and new ideas such as GPU rendered UI to make the CPU free for real tasks. Windows 7 takes that idea and and develop on it, with new features (their quiet a lot of new features... multi-touch, superbar, windows management, is just like looking at a delicious cake far far away. If you look much closer than it's packed with new features.