When anything gets as big as reddit there will always be unsavory things posted - flying the banner of 'free speech' for so long and then suddenly doing a 180 is what has made people annoyed
Reddit is the natural place for the discipline of artificial moderation (using AI / ML to help moderate public forums) to develop. For example, an automated "argument detection" bot could intervene when two participants start going down the warpath, acting like a janitor who pushes two rowdy students apart when they start fighting. Or, a bot could detect when a post consists entirely of one participant insulting another and take appropriate action.
These are difficult problems, but Reddit is sitting on a goldmine of training data in the form of the human-generated moderation logs. Reddit should either hire the talent to develop such systems or partner with those who already have (Google / IBM / ...).