Campaign ads can talk about real issues, present voters with real information and be part of a communications process (along with the news media) that helps citizens make more informed choices about what sort of government they want in Washington, their state capitol or their city hall. Candidates are just not asking them do so.
There's nothing about the advertising discipline that says its messages must be negative and nasty. It is candidates and their tacticians who decide how to use this tool, and the common wisdom still is that negative ads work.
In 1992, the Clinton and Bush campaigns gave issues a place in the ad spotlight. Two years later, the pollsters and media advisers prescribe heavy doses of "who's-soft-on-crime," "who's-soft-on-Clinton" and "who-dislikes-government-more."
Distaste for campaign ads breeds more cynicism about all advertising. But until candidates think they can win with issues and a positive program, it looks like advertising will be blamed for their timidity.