With all these commands I'm always prompted to ask, "Why did God command this? Why does God say that?" And of course, it's certainly not sinful to ask that question. In fact, Jesus broadens the application (well, actually reemphasizes the already broad application) of a great deal of the OT law in his sermon on the mount. We do not only obey the letter (exactly what it says), but we obey the intent.
Yet, there is a way that it does become sinful. When we use our interpretation of "intent" to disregard the command itself. When we say "well, God didn't really mean it like He said it," it actually means this. And "this" is complete speculation.
Sometimes, we obey even though we don't know exactly the reason why God said a command simply because God said it. As slaves of Christ, God's command should be our delight to obey, whether we know why He's commanding it or not. We aren't "conditional" slaves, demanding to know every single reason why God says something and what He's doing, but we are slaves of Christ.
Deuteronomy 29:29 is often used by me in many contexts, but I think it's perfect for this one:
29"The secret things belong to the LORD our God, but the things that are revealed belong to us and to our children forever, that we may do all the words of this law.We don't know why for some of the questions of the Lord. But you know what? It doesn't matter. If it's secret, then it's secret and it belongs to God. But the things that are revealed through the 66 books of the Bible are breathed out of God Himself. They belong to us and our children forever, that we may do all the words of this law.
This is where true obedience lies. It's obeying even when we don't know exactly why, but trusting the Lord, that He has purposed our good and His glory in all things. It's freely confessing "I don't know what's going to happen, but I do know what you demand of me, and that's what I'm going to do, no matter what happens. I'm going to walk by faith. God, have mercy on my soul."
John Calvin, in his commentary on Genesis 3:1 says this,
Very dangerous is the temptation, when it is suggested to us, that God is not to be obeyed, except so far as the reason of his command is apparent. The true rule of obedience is, that we being content with a bare command, should persuade ourselves that whatever he enjoins is just and right. But whosoever desires to be wise beyond measure, him will Satan, seeing he has cast off all reverence for God, immediately percipitate into open rebellion.