I see pros and Con to this:
Pros:
- Very convenient to pick up the ammo that you need. No need to search through what guns you already have
- Can make gameplay faster where you just run through a building picking up the ammo that you need without having to stop.
- Ammo will need to be fully stack able (I have only played this game a few hours and if I saw this correctly, ammo was only stackable up to a certain point then it would take up another inventory slot)
Con :
- Will be harder to coordinate with teammates on ammo levels. If you automatically pick up the ammo, it might be easy to forget a teammate needs it more then you. You also might not be able to get a chance to ping the ammo for someone else. By the time you are close enough to know what it is, the ammo is already in your inventory slot.
- Your inventory slots could go away faster. (See 3rd point in pro case). Since the ammo is only stackable to a point, then if you have auto pick up, you might automatically use up another inventory slot when you didn't want to.
Edit:
Some how, the word con is censored? IDK. Also as another point, PUBG Mobile implements auto pickup.