Argh. The oil is not the caffeine. The oil is not (alone, or even predominantly) what makes the flavor. Also, beans that look oily are not oilier than beans that look dry. A bean that's roasted dark enough to produce an oily surface has had many of its lower viscosity oils volatilized, leaving only heavier oils. A more lightly roasted bean has not lost these lighter molecular weight oils in the lower heat (say, less than 435 degree bean temperature), so more oil is actually retained. Brewing methods that don't use paper filters will deliver these oils to the cup.
Personally, aside from not liking dark roasts in general, I don't like brewing dark roasts using methods that get the oil to the cup because I don't like the flavor that comes from a balance of oils that lacks the lighter weight oils. I do, however, very much enjoy a lighter roast brewed to yield the oils in the cup, because to my palate the balance of oils is better with the lighter weight oils not lost in the roast.
Beans stale relatively fast. Lighter roasts stale more slowly, and indeed are best a week or so after roasting. Darker roasts are best in about half that time. Oxygen and warmth (the latter affects the former's rate of activity in the bean) are enemies no matter what.
I think someone's being mischievous here, because claiming that regional distinctives don't matter, or are not what makes coffee good, borders on the insane. Charitably presuming that the poster is not insane, I conclude to mischief. Dittos for the idea that if there's not much oil visible on the exterior, there must not be any left inside either. That's backwards thinking, since oils are burned off and migrate to the surface only on darker roasts. How could less oil be present in a lighter roast that hasn't had those oils migrate to the surface and be burned off yet? Argh.