I used to think this was a good idea, too, but I realized along with others that you don't need to look down at your pouches to see what you're grabbing. You feel the weight of the magazine to check its ammo (already in the game), and you can maneuver it into your weapon with only the smallest bit of attention. For clip fed weapons, it's even easier, because you can feel the number of rounds you are grabbing. This would obviously need more attention because it requires more precise motor skills to load.
If this was implemented, it would be a nightmare to animate each sequence grabbing ammunition from a different pouch.
For a complete Kar 98k, you have to animate each pouch, which there are six of, and in each is a divider, so you would have to create 12 different reload animations alone. That's a lot, and it's really not worth it. I can imagine the G41 being an EXTREME nightmare as a result of this.
My preference: Conventional reloads, no pouches.