“This is what is meant by the verse (Tehillim 89:7), “For who in the heavens can equal God, can compare with God among the divine beings?” Said the A-lmighty, “If I wanted a sacrifice, wouldn’t I simply ask Michael, who is right here next to Me, to offer to Me a sacrifice? From whom do I want a sacrifice? From Israel!”
– Tanchuma, beginning of Parashas Tzav
The Kotzker Rebbe explains this medrash. Hashem does not desire the qorban itself. Mal’achim could make a far more perfect offering with no adulteration of intent. Rather, the qorban is in the decision to give. Hashem gave us the power to decide, and our handing back that which is truly ours is what brings us close to Him.