Keep in mind this is all my personal opinion, but I don't think I'd worry about. With my handheld electronics, I get pretty protective and use screen protectors (and full skins, usually), but I don't imagine the desktop's screen getting as much activity. Of course, you're also not sliding it into your pocket all the time.
I checked Toshiba Direct, and I didn't see any screen protectors for the AIOs there either, which is a good sign I think.
I don't really recall seeing scratches on public touchscreens (grocery store self-checkout for example), and those are even used by people who don't care about the screen.