I can't speak for anyone but myself, but the way I see the Scriptures, Torah must needfully hold primacy as a structural matter. It is the 'seed' if you will - The whole of the tree is originally contained in it's seed, governed by the plan contained therein. Ergo, what one sees in the tree must necessarily be of the seed... I don't know if that describes it perfectly, but I hope you get the idea.
Either Torah is eternal, or the whole Book falls apart. YHWH is the only contender for the position of god that I have ever found that declares Himself explicitly and forbids any change to what He said. Take that away, and there is no difference between Him and all the rest. If priests and teachers have authority to change it, then the very thing that declares Him AS GOD is rendered null. That is why He guards His Word so vociferously.
And if His word is no good, then neither are His Covenants. One disregards Torah at their peril.
By the way, verse 17 in the passages you cited is the key to verse 19. The New Testament doesn't promoting unrighteousness and ungodliness. There is a difference in living a righteous life because of an external law, and, having being regenerated by Christ within, living a righteous life because one's very nature has been changed.
So if you 'fulfill' the law by driving 55mph once, does that mean you no longer have to mind that law? I think you might need to reconsider what 'fulfill' means.
And as to righteousness, the definition of righteousness IS obedience to Torah - So, what is written on the heart must needfully resemble Torah, wouldn't you say?
How does Yeshua condemn 'workers of iniquity' when the very definition of 'iniquity' is lawlessness (without Torah)? If the law is 'fulfilled' and no longer serves a purpose, then there is neither iniquity as a matter of fact...
Either the covenants of the OT were made with ONE group - the Chosen People - or they were not.
I do NOT have to obey the speed limit in Jerusalem when driving in Denver.