You see, the problem is that demagoguery is effective. People by and large don't understand the details of policy and it is much easier to drive decisions based on emotion rather than reason-this is a biological fact. What is "hope" and "change" after all except vague appeals to emotion? As one side employs more and more heated and demagogic rhetoric without paying any political penalty then that will be a self reinforcing behavior and eventually the other side will become equally heated and demagogic. Thus, perpetuating the notion of equivalence and calling on calm from both sides rewards the most egregious violator and leads to perpetuation of the behavior.