There is certainly a lot of spiritual waffle on nikyo here. If in doubt - keep it simple. Of course nikyo hurts. Martial arts are about destroying people. Get used to it. The pain in nikyo is about as bad as pain gets for most people and that's why we like it. Admit it. For me, a good nikyo is one that hurts like hell when on, yet afterwards, little to no pain lingers = no damage. That is good nikyo. And to have no lingering pain you have to find a way to do it with minimum force - that is the real skill.