Yep, I had the same "I don't get it, but it works really well" experience late last summer, as I documented on my blog. The PBC is simply the simplest BBQ cooker on the planet. I've stopped trying to figure out why (a scientist couldn't either), and now I just enjoy brain-dead-easy BBQ bliss.
P.S. This is a phenomenon that allowed Noah and me to beat "The Godfather Of Ribs" (Johnny Trigg) in ribs and pork at a competition last summer, using only Pit Barrel Cookers, Kingsford blue bag, and *gasp* lighter fluid.