Knocking out nociceptors? It's not what I thought about. Knocking them out reduce available infomation to make decisions. I meant deliberate suppression of goal-shifting and brain resource allocation effects of nociceptors activity (in a sense proposed by Marvin Minsky). It is hard to evaluate effects of this change on child's pain aversion behavior, but I can hypothesize that this kind of pain control could be ineffective until "central executive" is sufficiently developed.

Edit: In the case of mild pain this way of dealing with it can be exercised on our current brainware.