Wasn't the ammo nerf because of snipers in the first place? People who would do things like start with a sidearm or something like the invective and then swap over once they got free ammo?
If that's the case then surely there was a better way to stop players doing that than ruining weapon changing mid game outside of that little exploit?? Aside from the sidearm ammo exploit I think the ammo situation with switching weapons was far better before.
When you're getting frustrated in Crucible and decide to change weapons to better combat how the other team is playing the last thing you want to realise when you open your menu is that you won't have any ammo.