Because it will be a really cool thing to do and we want to look for water.
But mostly looking for water
The idea is that over millions and billions of years, a lot of comets have hit the Moon. The water from these comets hits the surface and sublimates away… but if any settles at the bottoms of deep craters near the Moon’s poles, these permanently shadowed regions can act as a refrigerator, keeping the water from disappearing.