I know cuz it's easier to grind up fine, but I have a finishing grinder so I don't need to worry about that. If vaporizers boil off the active oil, and oil is a liquid, wouldn't moist bud be better for vaping, at least in the sense that you'd get more vapor (not necessarily more active ingredient)?
Here's the deal. Dry bud will produce more of the active ingredients but bud that is not overly dry will provide more taste for the first few hits and then when the bud finally does dry out, you then get most of the actives. Personally, I don't like vaping very dry bud. I much prefer vaping well cured bud, but not overly dry because I like that blast of taste that I initially get, and yet, I don't lose any of the actives in the subsequent hits.....best of both worlds.
Yeah you'd get more vapor. More water vapor. Which does jack shit. I'd think it would actually inhibit the vaporization of the actives since it first has to evaporate the excess moisture. The extra water won't help "carry out" more actives or whatever you're thinking. Cannabinoides are barely even slightly water soluble. Might as well just call them completely water insoluble. Some terpenes and flavonoids might carry over better with a little more moisture like lwien said but you need just standard dryness, not too wet not too dry. Extra water won't help.
Well in my vapour genie I store my weed in air tight space so it's not super crumbly and dry. I grind it real fine and fill a bowl. I find the first few hits are mostly just water. Not a lot of THC, Tastes pretty damn good though but once it's dry like iwien said you get active ingredients out of it. Unless you heat it up nice and hot on the first hit, than you get massive vapor clouds. Pretty hard to burn the herb to when it's got some moisture in it. But with my little lighter powered one I've only been able to get those high temps fast because I got a torch. A bic could never heat it fast enough.