I would suggest that the reason for the bony ridge in that area was to protect what is above it. Neanderthals and Cro-Magnon man didn’t have the convenience of a local meat grinder, and who knows what kind of tough skins the plant life had. You didn’t want anything ‘poking’ through that area while you were chewing it.
Now that we are more of an ‘agricultural’ civilization, the need for it has disappeared. Any part of the body not used, atrophies. Like my brain.
Not bad, although I would put that the other way around — as those characteristics disappeared (due to luck o’ the draw, iow chromosome lines vanishing, and maybe mutation) other means of eating had to be innovated.