Why don't incandescent light bulbs last longer then they do?
Some incandescent bulbs do last longer but there are some downsides to them. One way to make incandescent last longer is to increase the thickness of the filament so that it will not deteriorate as quickly. The down side to this is that it takes more energy to heat the filament and the filament does not glow as bright. These types of long-life bulbs typically glow an orange color. If you purchase a long-life incandescent bulb you might find that a 100 watt bulb only puts out the light of a 75 watt bulb while it consumes 100 watts. The amount of money wasted in energy with this type of bulb means you would have been better off purchasing a regular bulb.
Another way to make an incandescent last longer is to use a rare gas called Krypton gas. Krypton gas is denser than the standard gas used (Argon gas) and helps to keep the filament from deteriorating as fast. You will find that "premium" incandescent light bulbs contain Krypton gas, but unfortunately cost more money.