Marketing definitely influences consumer's desires about products and services. Marketing agencies "target" specific demographic groups to influence them to purchase products that are in fashion, in hot demand or the latest infomercial craze. For example, children and young adults are targeted by marketing agencies to develop new desires for video games, iPod's, Elmo's, and Nerf Guns. None of these items falls under the preexisting need criteria. Adults are targeted to buy big ticket items like fancy cars, vacations and the best label top designer clothes to wear that fits nicely on their slim bodies shaped through the newest diet pill.
Even better, agencies advertise cosmetic surgery to tell people they can look like their favorite Hollywood star. These are all examples of developing dew desires. In fact, even when marketing agencies do respond to pre-existing needs, such as food and clothing, the marketer's job is to convince the consumer to purchase the best. Assuming that travel is a requirement, marketing agencies spend a lot of money convincing consumers that they need a Porsche for their basic travel needs when a Ford Focus will get them to the same location.
Marketers create innovative ways to advertise cell phones by linking specific phones with popular entertainers or sports stars. The implication is that, if you use this cell phone you will be as "cool" as the entertainer. This has no relationship to whether a cell phone is a basic need.
Marketing does have a role in addressing real needs and making sure consumers are aware of their options to buy something basic or extravagant. However, in today's world, my impression is that the vast majority of marketing techniques are heavily weighed towards creating new desires as opposed to addressing basic needs.