Ads are helping companies to reach out to their customers, to evoke awareness and like. But is advertising important? ... The primary purpose of advertising is to communicate the existence of something, product/service that will serve people in some way. So advertising will be good even for the "ideal" society.
Yes, it can be harmful. But it can also be extremely beneficial to society. Advertising is an incredibly effective and powerful way to spread the word about important issues and products, such as AIDS awareness, diabetes monitors, tobacco and alcohol risks, and other health-related concerns.