As mentioned, I've begun the process of trimming smaller "popcorn" buds from my first grow and had a somewhat unpleasent experience last week with some material that I trimmed, hung upside down for several days, then kept in a sealed container for a few more days and then rolled up -- it felt dry and smelled great, but the smoke was harsh and didn't really "work". I returned again to the sages at rollitup to see what was crackin' on the messageboards and I came up with the following:
Curing can seemingly affect potency because often the first time the buds feel "dry", they really aren't. Once they start to cure and sweat, you will see how much moisture is left.
Curing is mostly for aroma and taste, but the first week after "drying" will still have some effect on the potency as the bud fully dries.
If the above is not reason enough, here is a more scientific explanation:
Drying bud converts crude acidic THC from its nonactive form into a neutral pH psychoactive substance. Each THC molecule has to lose it's moisture content in order to become fully psychoactive.
[Editor's note: Starkes suggests up to 95% of the cannabinoids will remain carboxylized in dried and cured plant matter]
When the water exits the bud, the THC becomes slightly different in molecular structure. As Fatima mentioned (See this thread from overgrow.com), heating can make THC readily active by immediately vaporizing the bud's moisture content away. However, as Fatima also mentioned, aging is important too.
First the bud is "dried", but can still contain some moisture within. By using the "cure", the THC slowly becomes psychoactive. Curing builds a more uniformly dried bud with a better burn and taste. Almost all the THC converts to the usable psychoactive cannabinoid over the alotted time, without the degradation from drying the bud rapidly with heat.