Isn't accusing someone else of being negative a form of negativity? Try to imagine a world without negativity:
PROSECUTOR: I intend to prove that Mr. Doe killed his wife.
DEFENSE: Oh, you're just being negative. Why bring up the past?
PROSECUTOR: You're right. I'm sorry. The state drops the charges.
Any new law, spending project, or candidate will have an upside and a downside. Conversely, not passing the law, project, or not electing the candidate will have an upside and downside as well. Both sides of any controversy have to talk about the positive and the negative of the issue at hand.