Okay, let’s say there is water on the moon. So what?
It means that fuel for space ships and oxygen can be manufactured on site.
LEMONADE STANDS!
It means that lunar colonization is possible and (relatively) affordable.
Hauling materials up the gravity well from Earth to the Moon is expensive, in terms of money and fuel. The most important materials we would have to haul would be air (which is rather light, and can be compressed) and water (which is heavy, and cannot be compressed). With water already on the Moon, we can haul up seeds and tubing, and thereby grow foodstuffs; with foodstuffs, the lunar colonists can feed themselves; if we had to constantly haul water up, we'd exhaust our terrestrial patience and resources.
We'll have to haul up the initial makings for solar cells and ore mining, but with the nigh-unlimited sunlight, the colony should be able to generate plenty of power, and contribute resources for building satellites and spaceships, necessary for mining the Asteroid Belt.
The idea of building spaceships at the bottom of a gravity well is insane. Better to build such things in Lunar orbit.
Rah, rah, RAH!!!