Saying God's law is perfect and leaving it at that is not thinking critically about the issue. There is more to God's law than the 10, all can be spoken of as perfect, yet clearly our obligation of them differs. When you intend to isolate the 10 by calling it God's law or perfect you are in essence saying it is a special kind of God's law and a special kind of perfect that is separate to the rest of law. Where is the scriptural support to separate the 10 outside of the covenant they are created in?
All law points to Christ from sacrificial laws, separating laws/food laws, ceremonial, etc... (there are no such labels in the bible but you get my point). They have instruction for inside its covenant as well as deeper meaning that extends outside.
Our focus should not be the surface but the deeper layers. to resist killing lying, stealing, etc... these are good in themselves but they do not address love and that's where our focus should be "Written upon the heart" means living and dynamic and guided by the spirit not static and written upon stone. The product may be similar but we should be guided by the spirit not by tablets written on stone.
our focus should be love centric not law centric. Gal 5:14 tells us the commandment to love your neighbour as yourself fulfills all law. This is a heuristic approach to law, it is not an list of do's and don'ts, but a method to calibrate your actions that implicitly requires engagement to your surroundings as well as to the spirit.
The 10 simply don't cover the nuances of life that need to be addressed to have impact. The fact that I didn't lie to a person, steal from them, kill them, sleep with their wife, etc... is all well and good but it does nothing to engage with that person and address their needs. Our actions calibrated to the 10 are also not enough.
This a poor excuse to withhold goodness. Christ says it's lawful to do good on the Sabbath, he did not say only if it can't be put off. Why put off goodness? This is the sentiment I am speaking against. Look around in a mile radius. How many are in spiritual darkness? These are akin to sheep trapped in pits and we should treat these cases seriously not just put them off. Rest is fine but when an opportunity for goodness is upon us why put it off? It feels a bit like crossing the street like in the good Samaritan. If instead of being law driven we are love/goodness driven then it is lawful. Christ teaches this, Paul and James also teach this so what's the hesitation?