Sometimes, to save a great deal of time and energy, I'll chuck one of these pre-drilled blocks in my lathe. Using a test indicator I'll slowly rotate it and get it as concentric as I can, at least within a few thousandths. Then clamp it tight and turn as if I had drilled it and fit the stem myself. Occasionally, I'll fit an acrylic stem, maybe a band or some trim to jazz it up. Using this technique saves the labor of drilling the bowl, turning and drilling the mortise and fitting the stem. As long as the block has a properly drilled draft hole, they really aren't much different than how I'd drill it. And they actually make a great smoking pipe, but usually need a rusticated finish due to flaws and lack of grain.
For the record, I've never sold any pipe made in this manner. I always start with a solid block and do everything myself for commission work. I reserve pre-drilled pipes for my own use and for practicing on bowl shape, staining, finish, etc. It allows me to be artistic while dispensing with the laborious (boring) mechanical aspects of bowl drilling and stem fitment.