In some cases it's clearly superior. If you have left thumb on left stick, and right thumb on action buttons, and you want to add another direction input, tilt is an ideal input method. eg. Move forwards/left/backwards/right on left stick, fire gun with face buttons, and duck/peep over cover/jump by dropping/lifting the controller.That might be true if moving your controller was actually superior to moving a thumbstick, but it's really just a different method of control.
Whether MGS4 could be ported effectively to a platform without motion controls depends entirely on how they're used.