At one point it was thought that it would be a good idea to shut off pain, replacing it, perhaps, with some sort of warning message. Then it was discovered that pain was the warning message, and to remove it carried the danger of apparent invulnerability. The best that could be done was to make the message less… distracting.
…One could imagine a conscious nervous system that operates as humans do but does not suffer any internal strife. In such a system, knowledge guiding skeletomotor action would be isomorphic to, and never at odds with, the nature of the phenomenal state — running across the hot desert sand in order to reach water would actually feel good, because performing the action is deemed adaptive. Why our nervous system does not operate with such harmony is perhaps a question that only evolutionary biology can answer. Certainly one can imagine such integration occurring without anything like phenomenal states, but from the present standpoint, this reflects more one’s powers of imagination than what has occurred in the course of evolutionary history.
--Sam Hughes, Fine Structure
From a nonfictional paper.