At the end of the day .. if something does not break, why change
it? If Windows XP is working just and good, why introduce so many
patches and later introduce Vista? 
It is clear there is something deficient in the system of God's law
and commandments.
Read the context of Rom 7:12 from NIV:
11For sin, seizing the opportunity afforded by the commandment,
deceived me, and through the commandment put me to death. 12So
then, the law is holy, and the commandment is holy, righteous and
good. 13Did that which is good, then,
become death to me? By no means! But in order that sin might
be recognized as sin, it produced death in me through what was
good, so that through the commandment sin might become utterly
sinful.
Read my emphasis in red which is hiliarious! Shaul like suaning
the law liddat. Do you agree when people suan you, they will say
you are very good and then they will end with .. yea right!

And the context of Rom 7:16 from NIV:
14We know that the law is spiritual; but I am unspiritual, sold
as a slave to sin. 15I do not understand what I do. For what I want
to do I do not do, but what I hate I do. 16And if I do what I do not want to do, I agree that
the law is good.
Read the condition clause! Read the fine print!
The law is good ONLY WHEN you do what is right in Shaul's
worldview. In his worldview, we are slaves to sin so we find it
very hard to do what is right and we keep on doing what is hateful
to us, i.e. live in a life of sin.