Some people get an idea in their heads and it's bye-bye reason. One of the sillier ones is the idea that negative campaigning is bad. Women in particular seem susceptible to this.
No doubt it would be bad if all campaigning were done this way. But surely no one expects candidates to expose their own weaknesses. And if the people who are crying like babies over the Swift boat ads and the money they got from people connected from Republicans would kindly line up some Democrats to give to them instead, I'm sure the Swift boat veterans would be happy to take that money instead.
And of course George W. Bush is an incumbent. You can see what he has done as President, for good or ill, and the net score is positive. For John Kerry OTOH you have only the claims of a demonstrated flip-flopper who has shown the willingness to betray even his band of brothers on the Swift boats for his pathetic political career. Under those circumstances, why would anyone believe a thing he promises?
Beware of those who complain about negative campaigning. They have something to hide.