Question:
It seems to me that the more refined and spiritual a person will be, the less he will need commandments, as he himself will understand what is right and wrong. Just like a child needs so many more rules than an adult.
Following this logic, why do non-Jews need only seven mitzvot while Jews need 613?
Answer:
Good question. Rabbi Yehuda Loewe (the "Maharal") of Prague asked the same question some 400 years ago. He explained that the true expression of G‑dliness is freedom. The human soul is G‑dly, therefore it is free to be whatever it wants, to rise to the highest heights, or, G‑d forbid, the opposite.
Therefore, whereas animals know their rules by nature and generally stick to them without being told, the human being must be commanded. The basic structure of his laws are seven, because they are meant to limit him within space: six directions plus the space within which he stands.
The Jewish soul, because it must be a light to the nations, expresses the freedom of G‑dliness even more. Therefore it must be restricted within time, as well. These are the 365 prohibitions, corresponding to the 365 days of the year (the year is the basic measurement of time).
Rabbi Tzvi Freeman for Chabad.org