Oh, I know how easy it is to just stand in one spot and then zoom back and forth. Often, you'll get the composition you want, but not always. Plus, you'll be missing out on other visual perspectives if that's the only thing you do. The idea is to mix it up whenever possible. Zooming AND moving should both be tools in your creative arsenal.
BetterPhoto staffer/instructor Kerry Drager, who is also co-author of my upcoming book The BetterPhoto Guide to Creative Digital Photography, regularly applies this approach to his wide-angle photography. Shooting at a distance just doesn't provide the same unique perspective. That's why Kerry often refers to the wide-angle as a "creative close-up lens."
As an example, consider this photo, captured at Morro Bay (along the California Coast) just moments before sunset. Kerry set up his camera - on a tripod - low down and close up (within an arm's length away) to this wonderful old multi-painted boat. He also used a small aperture (f/19) in order to get a good depth of field - sharpness from near to far.
By moving in tight with a 20mm lens, he was able to create the wide-angle's "exploded" perspective. That means the subject appears disproportionately large in the foreground, while at the same time, story-telling details can be seen in the background.
Whether you're shooting wide-angle or telephoto, have fun "zooming" the old-fashioned way!