Shortchecking is the sort of thing you would request to do if you were doing a hidden city ticket scam (e.g., buying a ticket from City A to City B via ATL, then getting off the plane in ATL and not taking the connection (because the fare from A to B was cheaper than the fare from A to ATL).

However, there are times when I think it is legitmate to short check bags so I wish they would allow it. For example, if you live in ATL and you're flying SFO-LGA, for example, via ATL and you build in a 3 hour connection, you might well want to run home and change out your clothes . . . so you would want to short check your bag to ATL then recheck it once you repacked. I'll admit this would be the case with a tiny minority of people, but it's not like every instance of short checking is evil or devious.