Don't you know that Jesus' teaching on the Law was for the Jews in the kingdom age? OOOPS! Sorry, some of my former dispensationalism coming back to haunt me.
It seems to me that Jesus' point was the same as the point of the original giving of the Law - to show the standard of God's righteousness. "Be ye therefore perfect, even as your Father in heaven is perfect." The result would be that we would recognize that we fall short. This is step 1 in gospel preaching.