It is useless to our survival that we have pain receptors inside of us own digestive systems. All it does is give you pain that you can do fuck all about. It would hinder an organism to be in the agony of either excessive wind or a foreign body in the intestines. In fact, reflexes are all we need in this situation because there is no evolutionary advantage to consciously taking care of the problem. Even if we can do it now with medical science, the transitionary stages would have been useless to an organism. It would simply be withering in constant pain whilst predators were eating its children.

It's obvious, give it up atheists! There must be an intelligent and loving force behind our design!