I wouldn't. What's to stop someone from opening the case, grabbing the guitar, then just shipping along the empty case? Plus, if case latches opened then what? Just go dumpster diving at your local GC and throw it in a box.
I wouldnt recommend doing it either. Boxes can be easily found at GC or local music stores.
Usually have the foam inserts in them as well.
Only reason I shipped mine that way was it exceeded size restrictions and the guy I sold it to said it would be fine and has had guitars shipped that way as well.
I taped the shit out of the case but Danyeo is right.....no way to really tell if someone tampers with it in route. I covered that case in all tape....
I am sure he had fun getting the guitar out.
But it made it around the world safely.