Lisa:
Most people think exactly as you describe: They think of how sensitive their feet are now and think they couldn't run true barefoot. I pursued it from a slightly-less-than-moderate perspective a couple of years ago. I learned two things very very very clearly:
* Once your feet are conditioned (meaning both the muscles in the feet as well as the skin on the bottom of the feet) that running was not only amazingly fun but things that would have hurt when I started I didn't even notice.
* To condition your feet it takes very deliberate and slow action.
I walked (only walked) outside barefoot almost every day for about 2 weeks before I tried any running. It was quite fascinating: My feet developed this somewhat leathery characteristic that was both tough and soft. They actually turn into the exact opposite of what most think they would: They're not tough or rough or full of calouses. It's this smooth, almost shiny yet tough skin.
Even if someone doesn't want to run barefoot all the time I think it's very valuable to give it a try. It can really teach things about form, landing softly, etc. It's quite astonishing: When the brain knows there is no padding there your whole body lands very differently to absorb the shock. It's fun stuff.
Jim