Exploration is a perfectly valid part of the gameplay loop

Back on the surface, Theo's greatest concern when it came to digging out the dirt was about leaving the space altered too much.

What use would he have of his land if it was all littered with empty holes, eight by eight by eight deep, wide, and long? That's exactly why, rather than just picking random spots one after the other, he kept digging out the dirt in a row, with a distant thought of one day bringing all of the ground within the outer courtyard of his claim to the same, perfectly even level.

Down in the mines, however, Theo's concerns couldn't be any different.

In the underground, he couldn't care less about leaving an uneven, complex maze of half-random holes, for he neither had any use for keeping this area clean and orderly nor would he have to suffer the sight of such ragged terrain anytime other than when he would go underground to mine more.

No.