I figure that it's ok to use the entire length of the uncut fork; and plan on doing so with my new tourer. Why would the manufacturer make a steering tube that is longer than you can safely use? More money to make, more lawsuit risk, etc.

Without looking it up, I recall that Sheldon had an older bike with uncut steer tube. He wasn't even bothering with spacers--just a lockring right above the headset and then the stem mounted several inches above on the bare steerer. Wouldn't win any beauty contests, but safety was never questioned.