Their aging properties are different than incandescent. Incandescent tends to just fail when the filament breaks. There isn't much change in the spectral power distribution, and hence the overall stability of the light source is quite good. Whereas with fluorescent and even LED, there's a decaying of the phosphors, so while it'll produce light for a longer time (probably) the quality of the light will suffer immensely to the point that I think the longevity claims are approximately useless crap unless of course you don't care at all about the quality of light.