The surface area of the moon is about the same as the continent of Africa. Think about all the different kinds of dirt you might encounter on Africa. If you were building a house in Morocco, would you want to rely on soil samples from South Africa?

Regolith properties vary based on location even with the samples we’ve got. It’s reasonably important to understand the local soil conditions before we start trying to land 10-story buildings on the surface. No other option but to send something up to learn that info. Cheaper to use a robot than a human.