Like all habits developed over millenia, just because something worked back then, doesn't mean it makes sense now. We had our cost/benefit evaluation slowly tuned to the environment that rapidly (i.e. over last few thousand of years) ceased to exist. A lot of problems we have with each other can be explained in terms of executing adaptations we had from the time where survival involved hunting, and not filling out forms.

Not saying that normal eating is obsolete - just that arguments from nature tend not to be too strong in general case.