Two factors in play; humidity and aging.
Many B&M's overhumidify their smokes. We can speculate on the reasosns, but I believe most think they are doing the end customer a favor. Lots of guys don't have anything more sophisticated than a plastic bag, so as the smokes dry out a bit, they smoke fine. When you put them in your humidor, after a few weeks, they are in much better shape RH wise, and probably smoke better.
Actual aging won't happen in a couple of weeks. At least a year, sometimes more, is required to cause much change in the flavor of a smoke. While smoke smokes age and tremendously benefit from some down time, some smokes don't. For example, Padron premium smokes (64's, 26's, etc.) are made from carefully aged tobaccos and are basically ready to go as soon as their RH stabilizes. Point here is that "it depends".....
Have fun - B.B.S.