(Hell, I've been at one plant where PC side of the automation still ran on NT 4.0! The customer is reluctant to replace that machine because the interface to the plant automation is a freaking ISA card, and it has become rather difficult to procure a motherboard with an ISA slot.)
It's easy to tell people to update, but in some cases it's just not that simple. (OTOH, the plants I know about are not connected to the Internet.)
And don't get me wrong, I totally agree that it would be better in so many different ways if these machines were upgraded. But some users basically have no choice.