It's not sad at all when XP does the job and it would cost ridiculous amounts of money to update for no benefit. Now, waiting until the product fell out of support was a mistake, but Microsoft failed to produce a compelling upgrade for XP, period. Even Windows 7, which people generally like, doesn't run on the same hardware as well as XP if that hardware is older, which XP computers are going to be. And Windows 8? Aside from whatever bug fixes or improvements to the kernel might be involved, there is not one thing in Windows 8 that does not exist solely to serve Microsoft's interests, regardless of what customers want.
You can't blame MS when the customers don't see the value in upgrading, because from their point of view, there wasn't one. Now that XP has been sunsetted, everyone is worried, and there are a lot of companies that were very foolish in not moving to a viable and supported solution... except that in some cases, there literally isn't one.
There's a tremendous amount of legacy software out there that does the job and doesn't need a newer OS. A few years ago, one of my kids had use a portable brain wave monitor for a couple days, and was issued a device that he would be hooked up to, and guess what? It ran Windows 2000. I wasn't surprised at all. Windows 2000, as an OS, was one of the most solid releases Microsoft ever had (not necessarily the userland stuff, some of which was horrible, but the OS itself was fine).
By the way, the monitor found that everything was normal, my kid's just weird. ;-)
I would imagine those devices are probably still in use, and why not? Windows 2000 was a perfectly solid OS and was very secure on a non-networked device. XP didn't suddenly become not a good OS, Microsoft just pulled the plug without offering a good option for people with old hardware that didn't want to (or couldn't afford to) replace it.