I agree, if you need to have a light on continuously for times in excess of an hour, I don't think a flashlight is what you are looking for. A Coleman latern might be more appropriate. However, if you did need to use a flashlight for in excess of one hour at a time you are going to need spare batteries and I would rather have really small litium batteries than big D-Cells. You can carry a box of a dozen litium batteries in a box that isn't much bigger than a single D-cell.
Have you ever turned any flashlight on for a solid hour ? I never have but I would guess that a cheap D-cell flashlight wouldn't last much longer than the Surefire and produce far less light to boot.
Lights are tools, and like any other tool, you need to use the right tool for the job. Surefire flashlights provide very intense light, with a very high quality beam, in a small and reliable package. If you want extremly long run time, Sure fire has the answer to that also. You can buy a new LED head for most, if not all, Surefire flashlights. But, there is no free lunch. In exchange for long run time, you sacrifice intensity. This is just how the physical world works. You have a given amount of power in that battery. You can either have a lot of light for a short period of time, or less light for a long period of time. You can't have both unless you increase the size of the battery while still using the same battery technology (bigger isn't always better when one technology is inferior to the other as in a standard D-cell and a litium battery).