I think they changed it because of the triple tap perk is just to similar. They both reward snipers ammo for precision shots but the difference is that white nail perk out shines triple tap. Thus making all other sniper rifle useless. So instead of leaving as it is, they'll change white nail to make all other sniper somewhat useful... Why would we use a sniper rifle with triple tap when we have blackhammer with a better perk? I think they just want to make that difference and force us back to using ice breaker on bosses. This explains why they increase the time for ammo regain. They want us to spend more time waiting. Remember, each guardians spends around 3 hours or more playing?