Why Do Mitzvos; Naaseh V’nishma

Many people perform mitzvos just because Hashem said so. Yet they celebrate Shavuos as “Zman Matan Torasenu”. The Torah never identifies Shavuos as the commemoration of the giving of the Torah. Why don’t they celebrate the YomTov just because the Torah tells use to??
I think this underscores how people instinctively know there is indeed meaning in mitzvos aside from the Ratzon HaShem. He commended us in meaningful acts, and His commandment is what makes those acts binding and relavent. However those acts are meaningful even on our level.
Some people understand that the meaning in Mitzvos is in the very fact that they are doing Hashem’s will: Sheamarti v’naaseh ri’tzoni! In fact, it’s true. Not only is that a good reason for performing Mitzvos, it needs to behind any performance of Mitzvos. Performing a Mitzvah only because it appears personally meaningful (i.e. ” I do those Mitzvos I appreciate and not those that I fail to understand”) is not serving Hashem. It is doing one’s own thing. Perhaps you can call it self-service; service of one’s own self and intelligence.
However there are levels in that. We can say “the police forbid me to run a red light and I obey their will”, or we can say “the police have set a system to enable safe driving on the road and I obey their will”. Same result, different experience. We believe that enlightened doing of Hashem’s will is more meaningful than unenlightened doing. Moreover, it is Hashem’s will that we understand His mitzvos, as well as our poor minds can. For that reason we explore the meaning in mitzvos.
Mitzvos have two parts; the action itself and the meaning that action embodies. Indeed, we believe that Mitzvos essentially are the embodiment of ideals.
Human nature, however, insists on ritualizing Mitzvos, stripping them of meaning. A perpetual tension exists between our minds and our natures, where our minds pull to perform Mitzvos of content while our natures try to have us do those acts by rote.
The Malbim explains “Naaseh V’nishma” that Naaseh refers to our commitment to do the Mitzvos no matter if we understand them or not. Even if we cannot stand them! “Nishma” refers to understanding the meaning of the Mitzvos, appreciating their significance and connotation. Through action, performing the Mitzvos, we reach understanding them. (- A pretty heavy thought in its own right!)
The Tashbetz explains that indeed, did not intend to proclaim that we would hear what the Mitzvos are after we fulfill them, that would be impossible, rather we were saying that we would perform them and then appreciate and understand them.
So Yes, we do need to understand the Mitzvos. At the same time, our commitment to fulfill them is unconditional. We will do first, then understand. Naaseh V’nishmah!