What Yoda, and the Jedi seek to accomplish, is to strive for the goodness of being pure, without ever wanting to use their power to commit evil acts. So they abstain from the virtues of human nature, which is in itself abnormal. And, quite frankly, cannot be done. The only way is to accept human nature and believe in oneself that virtue will come naturally. But the Jedi would never accept that, and it is a blow to those like Kylo Ren, and Anakin who want it both ways.
Just like the priesthood, you want to become a Jedi, you have to give up all emotion.