Yeah, it does seem to make a lot more sense to shrink wrap the dirt and pot, doesn't it? Problem there is presentation. It's interesting, to me anyway, to watch markets evolve. Years ago, you'd find these mass produced trees shipped in initially with a covering of moss. The moss would, of course, die with inadequate care and the on shelf presentation would lose because of that. Gravel is a relatively new "innovation" in mass market bonsai. Initially, they shipped with wrappings, but no matter how they were packaged, the gravel would shift, again looking a little messy and taking away from the on shelf appearance. I think this is mostly why things are being done the way they are now, and probably not for any other reason.