The Ten Commadments
At first glance, the Ten Commandments consist of highly contrasting types of mitzvos. The first commandments, “I am God, your God,” and the prohibition against idol worship address the most spiritual matters related to God's unity. The other commandments, however, consist of such simple instructions as “You shall not murder,” and “You shall not kidnap,” which are precepts of basic human decency.
God placed these two contrasting categories of commandments together in the Ten Commandments to indicate that the Giving of the Torah accomplished a union of that which is spiritually "above" and that which is physically "below."
Prior to the receiving of the Torah the spiritual and material were two separate realms incapable of merging. But when the Torah was given, God nullified this decree, empowering the Jewish people with the ability to unite “earth” with “heaven,” by performing mitzvos.
The Patriarchs, who lived before the revelation at Sinai, fulfilled many mitzvos with material objects, but they did not have the ability to instill sanctity into the materials themselves.
The primary purpose of the mitzvos performed by the Patriarchs was to cause a spiritual revelation. The goal, however, was not to change the material object. For this reason there was less concern about the precise way in which a mitzvah was performed.
However, the mitzvos we perform now do have the power to reveal sanctity even within the material object so that the physical substance itself acquires holiness. Thus, the precise details and exact requirements are necessary to ensure that this goal is achieved.
(Based on Likutei Sichos vol. 3, p. 887ff.)