There are some definite benefits in the approach. The biggest win is the combination on non-realtime systems with realtime components (well soft realtime anyway, hard realtime is a step to far as yet) such as combining windows and it's graphics capability with a control system in one box. By using hypervisors there is a reduction hardware costs while overcoming windows piss poor real time performance. Another advantage is segmentation, so you can incorporate a hardened OS to run your secure system with your less than secure industrial control system.
The important thing has been the increased support of VM(Actually they are called Hypervisors) within the processors themselves, especially Intel.