While with pistols this is more or less an affectation, short barrelled submachine guns (especially the uzi) are driven up by recoil (and I think gasses escaping from the barrel) to such an extent that it does often make sense to turn the weapon sideways if you are firing on full auto and trying to say, kill a room full of people, as the gun will be forced rapidly (and I do mean rapidly) sideways. But of course aiming is a total crapshoot with these types of guns anyway. Thus spray and pray.