It seems easier for one politician to bash another than to engage in an intelligent debate on something.
Elections have a tendency to dumb down issues and fixate on stereotypes concerning political parties or leaders who lean to "the left or right."
If one can make a certain politician look worse than oneself, then the attacker wins because "he looks better by comparision".
Arousing negative emotions and attitudes seem to be the favoured tactic rather than well reasoned and well researched arguments.
The demonizing and generalizing give a bad taste in one's mouth for politicos and political parties. That's why many choose not to vote at all.