General UL principles lean to minimizing as much as possible, and stuff sacks scan add up, especially the old tough PU coated Cordura bags. With the cuben and silnylon bags available, it's not as weighty a problem (nice pun, eh?).
The bags in my kit are there to organize and/or protect the items--- or to protect everything else from what is in the bag. Dirty cookpots and nasty-leaky stuff like DEET and peanut butter need to be corralled. I do end up with about 5-6ounces of stuff sacks and ziplocks. I like to have everything in it's place and not spending 15 minutes and the aggravation of turning my pack inside out to find one item. I have things separated in systems: latrine, hygiene, small clothing, insulation, essentials, cook kit, food, and a small ditty bag for odds and ends.