Hello guys, I'm Spiral's friend with the cigar experience. He passed on the question, and while mostly I agree with him, I figured I'd add a bit of clarity.
There are several reasons why humidors are not optimum storage devices for weed. One is that the optimum relative humidity for weed is much lower than it is for cigars. It IS possible to set a humidor at a drastically lower RH, but it requires a lot more work and some modifications to the humidor, such as an air conditioning system or other way to lower the humidity. Humidification devices that are not filled can work t a degree, but not all the way- the optimum RH for tobacco is in the 64-72% range, whereas for weed, it's in the much lower 30-35% range. So really, it's not that optimum for storage considerations alone.
However, what's more important is the reason why marijuana users store marijuana and why cigar smokers store cigars. Often, the reason is the same- they buy more than they can consume in the near future for a better deal. But there's a lot more to it than that for cigar smokers. More often than not, people who invest in a humidor are interested in aging their cigars. Aging a cigar by keeping it in a proper environment for months or even years can drastically change the way the cigar smokes. First of all, it brings out the oils of the leaf used for the cigar. This has several ramifications. The first and most obvious is that the oils won't burn the same way while smoking, which cuts down on clogging and creates a better draw on the cigar. Secondly, the drawing out of the oils also serves to bring the flavors of the cigar more to the forefront of the palette, making for a more noticeably complex and tasty smoke. Finally, because of the lower concentration of oils inside the leaf, the tobacco doesn't create as thick a smoke, creating a milder smoke that has a much smaller chance of knocking you on your ass. This MIGHT work to a vaporizers advantage- bringing out the meat of the marijuana to more easily vaporize. But that's pure speculation- I don't know enough of the chemistry behind weed to say that with authority.
The second predominate effect of aging cigars in a humidor is the transferance of flavor from the common spanish cedar lining to the cigars. The lining material, unless it is non-porous, will contribute to the flavor. Spanish cedar is preferred because it gives a very nice light spiciness to a cigar, as well as a pleasant woody undertone. There are a few that do not use spanish cedar, mostly travel humidors with form fitting cushions, but those ones are meant purely to keep a cigar properly maintained and protected during transit, not age a cigar. The only cigars meant for aging that don't use spanish cedar are Davidoff humidors, which use a non-porous material so as not to affect the flavor of their cigars. Davidoff believes that their cigars are perfect as is, contrary to what pretty much everyone else in the world thinks when it comes to aging. So those would not affect the flavor. But ask yourself- do you want your weed to taste more like wood when you vape it?
Basically, the payoff just isn't there for keeping marijuana in a humidor. A cigar smoker might keep a cigar in his humidor for 1, 5, 10, or more years, and have a decidedly different smoke at each of those periods, and find one best suited to his taste. I know one guy who's taken to buying double the number of cigars he's going to smoke so that he can age them and start to have a selection that will, a few years from now, constantly be aged. Is anyone going to drop the money for a half oz. and wait a few years to use it? I find it doubtful, so any benefits that might be gained from aging will be lost because of the different approaches that marijuana users and cigar smokers have to their recreational habits. More likely, the weed will be gone in a month or so, before it has time to benefit from aging (if there are any benefits at all, which I don't know). It'd be an interesting experiment if someone wanted to try it, but that's it.
Sure, a humidor, with no humidification devices, will present a fairly good airtight container, at least as good as a well sealed ziplock bag, although probably with more air inside of it because of greater volume, so more air to lend to the decay of THC. It would certainly be a better stashbox than, say, a shoebox, and most definitely it would be more attractive. However, a mason jar would provide an even more airtight container, and if you like your weed a bit moister, then you can use a humidification disk. The bottom line is, getting a humidor to work for weed just isn't worth the effort.
EDIT- Missed the 0 in "10." Also changed some usages of "marijuana smokers" which, as a smoker myself, is sort of second nature. Upon reflection I realized that the majority of the people here probably don't smoke nearly as much as they vape, seeing as how that's sort of the general concept of the page. But hey, Fuck Combustion is a pretty subtle name, right? It's easy to see how I might've missed it, right?