To be fair, Windows 7 typically still has that network driver problem with new ThinkPads. Fortunately, ThinkPad is a good company, and they make it relatively easy to locate and download the right network driver to put on a thumb drive, if you don't have an install disk handy (happens more commonly than you suggest). This is easy if you know what you're doing, but, of course, next to impossible without some power user knowledge (it also requires access to another computer with a working internet connection and a thumb drive).
And also to be fair, XP is in a valid sense only one version out of date. Vista was a fiasco, and that's not just a meme -- Vista was released way ahead of schedule and still had a ton of known unresolved bugs. It was by far MS's most buggy release, and the whole thing was a disaster. Compared to the relative stability of XP, Vista was a step backwards. And while Windows 7 can rightly be called a newer version of Windows XP (and is better in nearly every way), it would be a stretch to say that Windows 8 is a newer version of Windows 7. Windows 8 is a fork into a different paradigm, and is so different it's not even comparable to Windows 7 along a number of dimensions.
All that said, XP is still pretty damn out of date, even with the latest service pack installed, and if Windows 7 is an option, it's usually a better one. Of course, XP uses less memory, so it may be suitable for particularly old computers. And for people that don't like to pirate software, owning a copy XP is a great reason to stick with XP (if it works well enough, why fork out the money for Windows 7?).