You are correct. And my belief is that this itself is a symptom of a political climate where parties are only out to win, whatever the cost.
If parties were to care about actual policies or helping certain people, they would find pragmatic ways to address them.

The best example is abortion, Rather than focusing on ways to reduce abortions or find a line to draw between "life" and "choice", this issue retains a binary quality and is constantly brought up as a wedge issue.
There are small portions of the population on either side that are immutable... and the rest simply do not hold it to that importance. Thus it is a freebie for activating and rallying a stubborn bloc.

Also this climate leads to politics of hate and fear. Even when politicians initially attempt positive ideas (I think both Obama and McCain tried to do this), it ultimately falls apart into a politics of "Who do you fear?!".
Mythical demons like "Welfare Queens" and "Evil Corporations" form and each side is rallied more around thwarting the practically non-existent enemy rather than working for their own cause- which could lead to common ground.

But people prove over and over, as much as they hate it, negative ads work and fear motivates.

__________________
"Man lives in the sunlit world of that which he believes to be reality. But unseen by most is an underworld, a place that is just as real... but not as brightly lit... A DARK SIDE!"
-opening from Tales From the Darkside