You seem to be heading down a strange path with bag sizes. It's now not very realistic. The Hiking bag is the same size as my work bag, and I can definitely fit more than 7 tins of beans in there. I'm a school teacher, and in the same bag I managed 60 compasses, my lunch, a first aid kit, a large water bottle, and other medical supplies including a spacer for an inhaler! If the bags are going to be reduced in size, other items need to follow.

My fear is you're going to make it too difficult for the average player, which will reduce the player base on survival/hardcore servers even more. On Official, if you need a sewing kit you just pop to a town and it's there. On hardcore servers we need to carry the precious items we find. We already have to make tough decisions, so this change is unnecessary. Clothing reductions were fine for realism reasons, but the backpack changes aren't realistic.