What I notice more than the charge cost is how it eliminates the rest requirement the spell normally has. Mister "You can not have a meaningful campaign if strict time records are not kept" is fine with the time-cost downside of a quality of the game being removed, so long as it is part of the limited and unpromised realm of found treasure. Extrapolating the logic of the rod bestowing the effect, I'm inclined to believe that using it also doesn't age the user 3 years, but perhaps telling which consequence is considered worth mentioning (admittedly this is already clarified in the unnatural aging rules).
That's another wrinkle, the text on DMG p. 13 is "Note: Reading one of the above spells from a scroll (or using the power from a ring or other device) does not cause unnatural aging, but placing such a spell upon the scroll in the first place will do so!" This only mentions scrolls, but the rules for crafting magic items includes "As DM, you now inform him or her that in order to contain and accept the spells he or she desires to store in the device, a scroll bearing the desired spells must be scribed, then a permanency spell cast upon the scroll... Wands and other chargeable items do not require permanency, and of course they are used up when all the charges are gone." Does that mean that the creator of a rod of resurrection had to create a scroll (accepting the aging hit) for each charge on the rod? Given that no demihumans can reach the level of cleric to craft such an item, we're looking at a human cleric with hopefully an 18 con (to survive the 50 system shock checks, even a 17 con/98%^50 puts us at 36%) and some kind of lifespan extension. With all that rigmarole, then seeing the party half-orc assassin need revival and 8 charges disappearing has got to be a gut punch.