Jews only, please. Why don't observant Jews obey this command of the LORD?

I believe it was because overtime as the Torah and other sacred scripts were revealed Rabbi's gained deeper insight in the the ways of G-d. And that you can put your trust in Him because he is loving and forgiving. The also started to see that it is G-d that decides which life He cuts of for committing these sins for he is the most perfect judge and everybody when they die must face him. Another more mechanical problem is the fact that another religion has build upon the temple mount. This means the laws cannot be administered in a Kosher way because their is not a temple for the Leviets the Sons of Aharon and Jonathan to govern Israel from. Most people like myself believe that Messiah will come and have the temple rebuilt and then from their the Messiah establishes his earthly empire and will rule the world out of Hakotel, Jerusalem or Mt Zion.