My Google-fu is failing me, but that was the official Apple Education Division (or some similarly named division) logo back in the early '90s.On the flip side, sometimes I think it makes it more interesting. I have an old Mac Plus with the bicycle logo burned into the side:
As for why companies/universities do that? To prevent theft. Pure and simple. They don't even think about resale value. It's just not something to think about. I mean, when the iMac came out, old Macs weren't "collectible" yet. Nobody had any reason to think of collecting them. (Yeah, a few of us nutjobs actually WERE, but we were oddballs - not something that any university or company would even knew existed.)
Yeah, they could throw a sticker on, but stickers come off easily enough. There are some that leave behind a "STOLEN" or similar when you peel them off, but that can still be removed with a little elbow grease. Perma-stick metal tags or melted-in stamps are effectively permanent. If police raid somewhere, those things will still be there easy to see.
Edit: A-HA! It was the Apple University Consortium. (Logo at that linked article.)