Paul doesn't seem to think too much of this idea either. Stand firm (in Christ, not in legalism), and do NOT let yourselves be burdened by a yoke of slavery.
He goes on to say that "if you let yourselves by circumcised, Christ will be of no value to you at all." Could that be stated any stronger???
It is not about circumcision, it is about depending on anything other than Christ. Remember Jesus' statement that we "cannot serve two masters?" (Matt 6:24) I don't think that this only refers to money! I do not think we can serve the law and Christ either. I think Paul agrees
To depend on the law, any law, any set of do's and don'ts, only alienates us from Christ. The only thing that counts is faith expressing itself through love. (Vs. 6)
So why do it? One reason comes to mind, fear. Fear that grace alone isn't really enough. Fear that God really will hold us accountable for our deeds. Fear that there really is a good/bad scale when we stand before God in judgment.
What is it that Isaiah says about our righteous acts? Calling them filthy rags? How does that play out on a balance scale? (Is. 64:6)
Or is it a fear of leadership as well? If we don't tell people to tithe, we might not have enough income. If we don't tell people to stay away from R rated movies (except ones about the death of Christ), they might go (and like them). Or perhaps it is just easier to preach works rather than the Gospel?
I am not advocating not doing good works. What I am saying is that any works not born out of faith and love are a wasted effort. And if any works born out of faith and love are meaningless, then wouldn't it make sense to spend more time on the why than on the how?
I wonder how many coaches spend their half-time talks going over the fundamentals? Don't they rather talk about the motivation to win? Isn't that how we get ordinary people to do extra-ordinary things?