This is such a neat suggestion if you expanded it to all containers and storage in general. I’d been thinking about it for ages, so I’m really glad you brought it up.
Forewarning - I haven’t played the experimentals since last year, so please excuse me if this is being worked on or, heck, even implemented already.
Grabbing something specific out of a full trunk, rucksack, duffel bag, etc. is time-consuming in reality - as anyone who travelled with a fully-packed suitcase could tell. I’d really like this to be reflected in-game as it would encourage players to think a bit more carefully about their looting and hoarding. This should scale as well, the smaller the item in proportion to the amount of stuff there is to rummage through, the slower it should be to retrieve: finding a lighter (say perhaps 1% of the volume) in a bag full of soup cans (the other 99% of the volume) should be rather slow. The inverse should also be true: picking one of the soup cans out (assuming they’re fungible) should be relatively fast.
Ultimately, I’d like this to lead to an overhaul of the inventory system in general. Rather than having a large single 100%-efficient void of a pocket on your person, your personal inventory should be divided into as many pockets as you are wearing. i.e. the couple small pockets on your jeans, the breast pocket on your shirt, and the ruck on your back should all be separate containers, each with their own maximum storage limits. You’re unlikely to be able to fill every pocket 100%.
This will also allow the player to drop containers and have them keep their contents, opening up interesting tactical considerations during gameplay. An encumbering rucksack, for example, could be dropped to get away from trouble, but perhaps you’ll also be leaving behind your spare ammo (will you have enough to fight if you still can’t flee?) and some of the loot you grabbed that night (was the fruitless effort worth the risk?), perhaps you could pick it up later when it’s safe (did you make a note of where you left it?).
For gameplay purposes, I’ll acknowledge that this might seem like unnecessary tedium, but when so many players spend much of the game plundering goodies and hoarding, inventory management mechanics should be as deep as your pockets.