HD, he doesn't mean higher focal length, but higher range (ie: 10x zoom vs. 5x zoom).

DJ, The wider the aperture (the lower f number), the more control you have. You can always select f/8 for a landscape on an f/2.8 lens. On a f/5.6 lens though, you can't go wider to f/2.8 to choose a thin depth of field, or control what's in focus, like the statue above. The f/2.8 will also let you use the lens in less light, but only if you're willing to sacrifice some depth of field. Since wide lenses tend to have lots of DOF anyway, this often isn't a major concern. This is why the above background isn't totally blurred. The DOF is large with wide focal lengths.

If you're strictly doing landscapes on a tripod and don't care about fast shutter speeds and thin depth of field, you don't need a wide aperture. Most people here shoot a variety of things, and would prefer the option of the fast aperture, so long as it's financially feasible.