From a design standpoint, even if you suspect that most riders will use relatively few of their gears, you don't know which gears, especially if you're selling the same bike nationwide. And entry-level riders might not know either. So having an abundance of gears doesn't sound like such a bad idea.
But it's definitely a subjective thing. A colleague of mine and I commute along nearly the same route. He swore that he uses all 21 of his gears on the same route that I prefer to ride on a single-speed.