The first answer is that right action is the result of sanctification, and not sanctification itself. Enforcing right action without having the sanctifying grace of God is like being religious without having the justifying grace of God. You've got a lot of works and nothing's really changed about you.
The second answer pertains to our own finite condition. By striving for holiness through these codes and standards, we have made the assumption that what we perceive about ourselves is an accurate depiction of our spiritual state. We may cry, "search me O God," but the "heart is desperately wicked, and who can know it?" It is quite safe to say nearly all Christians fail to see themselves as they are, for if they did, you could not stop the revival that would result.
The following is a quote from H.A. Williams:
"...the opposite of sin can only be faith and never virtue. When I attempt to make myself virtuous, the me that I can thus organize and discipline is no more than the me of which I am aware. And it is precisely the equation of my total self with this one small part of it which is the root cause of all sin. This is the fundamental mistake often made in exhortations to repentance and amendment. They attempt to conform me in my lack of faith by getting me to organize the self I know against the self I do not know. The result is that growth in self-awareness is inhibited. There is a sort of devilish perversity in this organizing me not to sin by means of the very thing which ensures I shall."