I feel the same way, I do it, but I also feel like it's a minor aspect where the gameplay is broken. It's the same as buying that 6th unit of booze for the extra barrel. I like the explanation about mountain home bureaucracy though. It's very dwarvenly and if that could somehow be conveyed at the embark screen it would set the mood -> this game is awesome, and you have only FUN awaiting you.
I like this a lot. ^.^
My point is that if you pay 1 for a sand bag, and then build your glass workshop, wood burner, furnace, bake some charcoal/coke, then finally convert that sand bag into a useful empty bag (and some random glass item), then the labor requirement is there. In fact, it requires a lot more labor than simply building a butcher's workshop and slaughtering a dog. So just don't empty the sand bag. USE it.
I wouldn't WASTE the sand - definitely turn it into some glass. But that's really not that difficult OR time consuming to do. 2 workshops, and you can do charcoal in tandem as you turn the sand into glass. Takes 2 dwarves only a couple of minutes to convert 10 bags or so. And the labor for that PALES in comparison to the labor of actually making bags from the START (if you don't bring thread/leather with you). Pig Tail route: You have to mine a farm, flood it, place a farm plot, wait a season so you can grow pig tails, wait until they're done growing, harvest them, process them in the farmers workshop, loom them, and FINALLY weave them into a bag. Leather Route: Bring some extra animals to slaughter or start with a hunter, build 2 workshops (butcher/tanner), and then try to make sure you're not wasteful while the butchered products sit out in the sun to rot, tan the hide, and then build a leather works to make the bag.
*shrug* I'm finding the different viewpoints on the subject quite interesting though.