If I were concerned about this issue, I'd think it would be wise to use a vacuum sealer like is used to preserve food for long term storage. It gets no more climate controlled than that.Thinking about this more, I suppose that if stored primed, there's not exactly much difference if it's stored with the powder and bullet in place. I mean, would that make a difference to the "freshness" of the primer? One could make a case there's less oxygen getting to the primer itself, but then again, the primers are getting plenty of oxygen in their OEM trays to begin with.
I suppose end of the day this is just a personal preference thing.