Think gesture input on tablets is new? The video below proves otherwise. It is amusing to see how the storage media and display technology of the day struggle to keep up with the innovation here, but it is still extremely impressive.
It's a demo of a system used to document PCB and IC drawings from the 1970s. Goodness knows how much this beast cost in the day, but it is stated it cut certain jobs down from days to a couple of hours, so, given the expense of hiring engineers, it would have paid for itself in a reasonable amount of time I guess.
OK, the display itself here isn't touch sensitive, and modern displays that detect more than one point being touched is a significant development, but I honestly can't see how much more effective modern tech would be with this application.
I was always fascinated by light pens and pen/panels (Koala Pad, etc.) as a kind. It absolutely seemed magical. While accuracy was an issue back then, you're right, the basics were all in place. What's amazing is that we still haven't gotten even pen-based accuracy/feel as good as pen/pencil and paper. I'll be getting my Surface Pro 3 to replace my Surface Pro 2 in August, and that's supposed to be a greatly improved experience, but I bet it's still not quite there yet.
Really like the feature that lets you map commands onto gestures of your own making.