Alright, think about it this way.

A expedition to the moon is VERY expensive. So traveling to the moon would have to be worth it.

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We know what the moon is pretty much made of, so that decreases the amount of attention we give it.

Now, if we were to make contact with Alien species in the future, I could see the moon being used as a base for transportation or anything else, but since that isn't a concern, it isn't a factor.

To put it simply, it costs way too much and we gain so little for it to be worth the money.