Three things:
1: They also nerfed almost everything else, somehow, be it with linked actions, turret changes, defence and offence debuffs, or something else, so the nerf is almost certainly not as big as you think, in relative terms.
2: They can adjust balance much more easily if it is underpowered or other things are overpowered.
3: It probably needed it. I've genuinely not seen a single nerf I can't think of a good justification for.