The answer to this question is that the highest purpose of the Mitzvot is to achieve awe of G-d, which means not just the emotion of awe, but total selflessness in relation to the Divine. While spiritual emotions are very beautiful, utter selflessness is on a much higher level. And the way to achieve this selflessness is precisely though practical Mitzvot, which are embedded in the physical world where G-dliness is hidden, and the Mitzvot themselves are sometimes quite contrary to reason, and also often very difficult to carry out.
The Sages also speak of practical aspects of the service of each of the Patriarchs, which are outlined in the Discourse. But primarily the service of the Patriarchs was spiritual.
Midrash Rabbah to Song of Songs 1:3.
All three kinds of Mitzvah can be seen as a form of Statute, which transcends reason, and thus should be carried out as a Command from G-d which we humans do not necessarily understand.
The discourse relates the word ‘Chok’, Statute, to ‘engraving’ in stone, which is a very difficult form of writing compared with ink on paper. So too the practical Mitzvot sometimes seem very difficult, and especially when they transcend reason.
