At the moment it does seem like we have way more bag space then needed when you get fully geared up, at the moment I don't even use the mountain backpacks because I prefer to use the hunting backpacks for both looks and the fact that in first person only servers I can use alt and look behind while I'm running without the giant mountain ones blocking my view. I used to carry like 8 magazines of ammo when in reality I probably only got to shoot like 2 mags at most during a firefight before both of us were behind cover or one of us died. Usually if you got hit, it would be in the chest area so everything in your vest, backpack, and shirt would be ruined including all my mags that I used to store in my backpack. Now I only carry 4 total, 1 in the gun and 3 in the pants pockets so that they don't get damaged. I think the reason we have so much space at the moment is because the game is still in alpha and there is a lot of content that has yet to be added to the game, I know that cooking is going to be added later on and I found a cooking pot that takes up 4 spaces, then there is those gas canisters, portable stoves, and match boxes that will most likely be needed to cook food, so eventually there is going to be more stuff that we will want to carry and less space that is going to be used for ammo/weapons/magazines. Also I haven't played the original DayZ mod but my friend said that when cars are added to the game you'll need parts to fix the car which I think will also add to the space that's taken up in your backpacks.