I have most of my sticks that I am aging stored in jars with no humidification device. I also have an upright humidor (not a jar) for dry-boxing. IMHO (assuming no cello):
Main disadvantages are:
- if there are more than a few cigars stored, then it is really, REALLY, easy to damage wrappers when you're taking cigars in/out.
- if there's a foam humidifier, then it is very easy to over-humidify the wrapper at the heads of the cigars, leading to mold.
- usually little insulative value, so your cigars are at the mercy of daily/weekly/seasonal ambient temperature swings.
- fairly difficult to get RH (inside the cigar) above 64% as the cigar's foot is pretty much sealed against the bottom of the can/jar. (Some jars have a cedar base to combat this.)
Main advantages are:
- cigar maintains the RH that it started with as the cigar's foot is pretty much sealed against the bottom of the can/jar.
- can be very inexpensive.
- better aging according to some (not because of orientation but because these typically have an airtight seal).
- looks nice and takes up less space on a desktop (for some).
YMMV.