Once you have a pdf viewer users want rotating pages, then bookmarks, then highlights, then form filling, etc.
That “just a pdf reader” is strictly worse than every pdf editor (which have to meet the minimum requirement of a pdf reader).
Apple’s Automator and Preview combo for me are indispensible and perfectly follow the Unix ideal. Automator composes well, and Preview does all the pdf editing well, and together they’re excellent software.
The version of Preview Apple just released on iPad is however basically just a reader, and do it hasn’t made itself relevant to any of my workflows or needs.
Full featured plus composable. That’s the sweet spot for the best apps.
Side note: I’m surprised there’s no ffmeg or imagemagik for pdfs (maybe there is?). Someone should build that.
The primary value discussed in the talk was electrical isolation since there's mains voltage in the appliance and the potential for shorts or inadequate isolation would require some kind of isolation, so a path that optically isolates the communication makes quite a bit of sense.
I'm also curious if other devices have gone this route.