For the same reason one visits a museum. If that doesn't make sense to you, then doing this won't either.

Unfortunately, I am working for an aerospace manufacturer that runs VAX VMS on emulators (which are quite expensive). We also run an even older operating system, OS2200.

The original VMS system manager who moved from 7000 series hardware to emulation was somewhat inquisitive, and we did install VMS 7 on simh. He retired and passed away some years ago, and none of his replacements have wanted to touch simh. I find that apathy appalling.

If you cannot learn from history, you'll have no future too, man.

For nostalgia sake. It's from the computing period when there was a great influx of good idea's but still a huge shortage in memory and storage.

For me, it's a chance to experience what it was like to use and develop software on these systems back in the day. For example, lately I've been writing some small apps and adding new kernel features to a variant of V6 Unix running on my PDP-11/05. It's humbling to see what it really took to be productive on these systems.