I believe I see your point now. Since power failures are (hopefully) rare, the additional bulb life added by maintaining the ability to cool the bulb during those rare occasions is negligent. As a matter of fact, a power outage that shuts both fan and bulb off should actually extend the life of the bulb. Since the single greatest factor contributing the the bulb's demise is electrical current through the filament -- and that stops as soon as the power cuts out -- any situation where the bulb is better from a longevity standpoint than when the bulb is on.

I think you've convinced me. ;\)