Man was created in the image of HaShem. As HaShem is free, man is free, can be free, must be free, will be free. HaShem wants free man to choose for Him, because he knows Him, because of his love for Him.
After the miracle of Purim, Am Yisrael accepted the Torah out of free will, for the first time in history. Servitude to HaShem, Avdut HaShem, is the height of freedom, if, but only if, it is acquired through Bechira, free choice.
At Har Sinai, the Torah was to a significant measure imposed. However, servitude to HaShem cannot be imposed. The imposition denies the essence of man, and the purpose of Creation. It takes the length of human history to resolve the paradox. From "Lo Lishmah" will come "Lishmah". Purim was an important step forward, but was followed by new forms of imposition. It could not be different. The resolution takes the full length of history.
The law is inevitable. To the degree that Divine worship is imposed, it does not derive from closeness to HaShem. The necessary result is worship that exposes the lacking closeness. This happened at Har Sinai - the Golden Calf. It happened throughout history. It happens today. See and understand.
