Quoted By:
Webbing on your hip belt can be very useful, but apart from that, not really. There are a few modular backpacks, but if you want to have optimal gear, you buy a backpack for your needs.
Heck, look at soldiers, they use a regular backpack (albeit some with webbing - pic related old usmc backpack).
I have a 85L backpack for my long distance trekking and mountaineering. I use the top lid as lumbar pack for day tours. If I want to extend that, I use a webbing sleeve I made for it.
That works really well. One pouch for map, compass, swiss knife etc. Another for a camera.
But replacing your main pocket with several small ones is silly.
