Handling an alum block with wet hands can cause some of it to come off on your hands where you decidedly don't need it. Having a handle and a screw on cover makes using alum post shave a breeze. Would probably also be fairly easy to throw into a toiletries bag for a trip which is a plus.
I use alum as part of my daily routine. I've used several different blocks over the years and this is the best I've ever used. The Omega stick wears all the way down to a nub with no hollow spots or breaking. The stick lasted longer than any block I've ever used.