Pack and gear are a balancing act. Some people with short torso length can be stuck with small packs. Large torso lengths are usually larger in capacity but the torso length is what determines how well a pack fits, not it's volume. Too much space and you want to fill it up. Too little space and you need to figure out how to make it all fit. Both the gear and the pack need to relate to each other. But there is always a level of tension between the two.