Non-camera bags for me are a carry solution rather than trying to disguise the contents. For bags I shoot from, I generally want something minimalist with no padding so it can squish down in volume if not loaded with much. Inserts provide the level of padding I find suitable for my needs.
One problem I recently solved was how to transport a DSLR kit and Leica M kit together. I.e for point A-B air/car travel. Many larger camera bags (backpacks, etc.) tend to be DSLR centric. The M stuff is too small and will float around with lack of sufficient dividers. And again, the bags are somewhat over-padded for my likes.
I ended up with a Tom Bihn Western Flyer, which happens to work well with Domke inserts and Tenba packing cubes. The DSLR gear uses the Domke inserts, the M gear is put in the padded packing cubes. At the destination I shoot out of other bags that roll up and store in the Bihn bag during transport. If I don't need to bring all that gear, but am traveling, I can pack half the bag with gear and the other half with clothes, etc.
I suppose, as is common with many photographers, one can never have enough bags. 🙂 Thanks to RFF I've come across some good alternatives to the typical photo brands, including both Filson and Bihn.