That's an interesting point about items outside the rucksack.
Only last Saturday I was window shopping in a large outdoors store (no, not GO) where one item that caught my eye was a budget backpack. Just looking, you understand.
Back at home, I searched for it on their website, where there was a large photo of a guy wearing one up in the mountains - and there was a stainless steel mug hanging from the pack.
I immediately thought that anyone advertising a backpack like that couldn't be the greatest expert in that field, and my interest in their product fizzled out.