It seems we are still forgetting that karma is not like merit on bitcointalk, as it's both positive and negative. -karma is more like negative feedback without the transparency and more often than not it leads to retaliatory negative feedback, and otherwise a negative feedback loop that draws more users into that loop. This is one of the reasons why the karma logs are not public. Users should be able to give -karma without retaliation, and open karma logs would encourage the opposite by default, and lead to negative feedback loops.
I support the idea of positive and negative karma on posts, although I understand it's not easy to implement, but not specifying which users gave the karma.