umm... Collectors would. Let's be honest here, the only people that are going to be interested are collectors of old pc games and to them, if you throw away the Jewel case you might as well throw away the game.
The shipping comment was more about recycling than collecting, but sure, having the whole unit makes the item. For me, the booklet, j-card, and CD are enough. I don't care about the plastic, but still have plenty of it. Even back when it mattered to me, if a jewel case broke, I simply replaced it with one of the same type. I suppose some collectors would say that if it's not boxed, it's not a game, but I don't have the boxes anymore either.
I could afford to pay someone to ship me 300 games on spindles with the j-card and booklet (if the person were willing to do that work for a few bucks extra.) The jewel cases would put the shipping weight way up and I'd have to pass.
I was more like a half-dozen-buckets PC game guy than a storage unit one, so I can't call myself a
collector.