I've never had a problem in not following the phases of the moon. Does that mean I'm saying that it doesn't work...? Not really, but it definatelly does not fit my schedules, and I'm not about to create gaps in my grow-cycles waiting for the moon, or for Saturn to rise beyond Venus, or waiting for the next solar eclipse....

With all the manipulation needed to pull-off an indoor grow, I really doubt the moon has much influnce on the plants, but more like stinky said...an easy to remember 'guide' for farmers, to bring the local crops to harvest on a predictable date. (being late in delivering product to an already full market isn't very profitable)
Could simply be that the moon makes it's easier to figure-out when you're supposed to plant, if you don't own a calendar.