God is ...
...not a maniacal maniac
...not a colossal killjoy
...not a jerk
The commands/laws/instructions/rules for living that He gives are "For our good…" (Deut. 10:12-14; 12:28).
When God says not to lie there is perhaps more to it than just that He IS Truth. There is the fact that lying hurts both the one lying and the one being lied to. It is a stressful way to try to live life not telling the truth.
When God says not to steal it is not just that it damages His plans for how man should "get" it is that stealing harms every person involved. When someone takes what you have it discourages you, it can be frightening, it makes it where you can't "give" as much and it leaves the potential to sour you. It causes the one stealing to be disabled from their own productivity and leads them to misunderstand respect for others.
When God says not to commit adultery, it is more than just that He wants one man to be married to one woman, it's the pain it brings into so many lives. The quick and easy divorce hasn't brought happiness into the American life. The free love of the 60's has not minimized the pain of unfaithfulness. Both have complicated every aspect of life.
Bottom line...when it comes to how to live...God knows what He's talking about!
"and His commands are not grievous..." (1 John 5:3).