Reporter badge, if does not have appropriate algorithm, might cause another type of abusement, and shady attacks.
Someone whom hate the forum, for whatsoever reasons, merit system, new rank requirements, might use their newbie accounts to do massive spam, then use their other accounts to run spam-report attacks.
I doubt people will do create accounts just for this dumb action. There's a lot of shitposters in a different discussion, they should go there instead of creating accounts for spam-reports. Just a waste of time

do you really need badges to motivate you do the right things? just keep on reporting,
Badges certainly aren't needed, but they would provide incentive for people to do more reporting. I have no doubt about that, because a badge would be recognition of an achievement of sorts, much like forum rank is or merits or trust.
Agree, There are users wanted to get every single achievement on this forum. There's nothing we can do but to support those people who aim to be better in this community by acquiring achievements.