3.7 introduced personal commodity inventory and backpacks that expand it, but right now they're attached to specific torso armors. Why is that, and is that where we're going with it? Are we going to be able to use other forms of storage, like utility belts or a one-shoulder sling backpack over a t-shirt?
TL;DRStorage is on the backpack armor only because it was the first implementation; the goal is for most armor and clothing, such as belts and pockets, to add capacity to one inventory.
The reason it's on the backpack is because it's the first implementation, and we had to put it on, ideally, the most meaningful piece of armor you have on you. And it kind of made sense because it was a big chunky box. You couldn't just hang it on your belt or something like this. So we put it on the armor. The goal is to allow pretty much any type of armor slash clothing to have some form of storage. If you put on your cargo pants, they have two pockets or four, whatever, each of them has a capacity and it all adds up to your inventory. Right now even smaller, lighter armors have a bit of capacity, so you can still loot a few things as you move through the world. You won't be able to make a fortune out of it, but you still can go pick up a key card or a fruit from somewhere or a mineable you find. You're not going to bring a hundred of them, but you can still pick up a few objects. The idea is to have the same kind of thing happening for a utility belt, as you say, or more like a clothing-type backpack that you wear on your back, or all of these items that you can put on you. And it all adds up to one inventory.