It seems more logical to me that morality is meant to make us improve.
A properly functioning society can also exist without morality (for example, societies that have slaves still continue to exist; they don’t die out).
If God is perfect, then in order for there to be improvement He has to create something that can improve. If there were no morality, then there would be nothing in which to improve. When there is morality, human beings have to struggle against their impulses. Their conscience tells them to be good, and the impulse sometimes tells them to do bad things. A person who refrains from moral sins improves himself and thereby completes this trait for the Creator.
Why do I need to add revelation and religious commandments to that?

I’ve written this thesis here more than once in the past (perfection and self-perfection). But it still means that morality is meant for other purposes and not for sustaining society. But if so, then again we have no way of knowing that without revelation. Without revelation, we might know only that one should behave morally in order to sustain society. But to understand that moral behavior is a spiritual goal for the Holy One, blessed be He, and not for us—that itself requires revelation.
In short, my claim is that morality as morality is not a plausible explanation, and therefore it is reasonable to expect revelation. Once there is revelation, it could have become clear to us within that framework that morality is the goal—but for a different reason, and not in order to maintain society. But in practice, the revelation that actually occurred in reality (at Sinai) told us something else: that the goal is Jewish law and the Torah, not morality.

It’s not so clear why there’s this jump to expecting revelation.
A washing machine doesn’t need revelation in order to serve me; it does what it was designed to do.
The Creator made us with a compass (a conscience) that tells us what is good and what is bad, even if that isn’t always what is directly good or bad for us, and that’s where self-perfection is needed.
If the Creator needs there to be self-perfection, it’s enough that He places us in the moral test; there is self-perfection even without revelation and even without telling us what He wants. We were given a very clear built-in compass.
If I build a robot to fold my clothes, I’ll build it from the start so that it knows that this is what it needs to do, without my needing to reveal myself and tell it.
In other words, I’m also asking why assume that if someone creates something and wants something from it, he creates it in such a way that it won’t know what it is supposed to do, and then requires revelation. There are two steps here, and the assumption isn’t very strong.

A washing machine has no choice. We were given choice so that we would use it. We are not programmed creatures. Therefore we have to be told what to choose. That’s it. I’ve explained what I had to explain.

We were given choice and conscience. Conscience tells us what is good and what is moral. The choice remains in our hands: whether to steal or not to steal, whether to improve or not. The Creator achieves the self-perfection through that.
The purpose of a washing machine is to clean clothes by means of the water and electricity it receives.
The purpose of human beings is to improve themselves by using free choice and conscience.
Where does the expectation of revelation come from?