Well let's discuss what actually happens during the drying and cure, in relation to water.
When the plant is chopped, it has it's maximum water weight that is it's circulatory system, much like the blood system in a human.
Then you hang it to dry. It dries from the thinnest outside parts that have the most exposure to air, to the thickest, inside parts of the plant.
After the initial drying of 3 to 7 days (common), the outer parts of the plant are crackly dry. If you handle the plant roughly at this point, good parts of it may break off it's outermost dry parts.
The thickest, and inside parts of the plant still contain moisture. This becomes obvious when you start your cure. After a couple days in the curing container, the parts that were crackly dry are now moist again! The water that was retained in the thicker parts has migrated to the the entire plant via evaporation and absorption or plain old fashioned "sponge" effect where the water bleeds into surrounding plant tissues.
During the cure, this remaining water is evenly distributed throughout the plant matter and evaporates at a slower pace than if left open to the air, as in the drying stage of the process.
This slow rate evaporation allows for the breakdown of some non-psychoactive elements of the plant into more psychoactive elements. This is a good thing.
Between the elimination of what water weight remains in the plant, and this can be as much as 10% of the original water weight, and the breakdown of the non-psychoactive elements into more psychoactive elements, two things happen that make the weed better; first the plant mass has slightly decreased. Secondly, it has more psychoactive properties.
The cure also helps make the plant better for our consumption by burning and inhaling. It will be smoother and have a richer taste. For exactly the same reasons as those in curing standard tobacco products.