Cookies are just there to keep some state between different HTTP requests to the same web site. This kind of state can be used for various things: keeping user preferences, keeping a user authenticated after login - but also to track user at the costs of his privacy. In other words, some use cases are considered important and valid and others are often considered bad.
Just because the bad use cases are possible cookies should not be banned. First, it does not solve the tracking problem since there are enough other ways to track users (like by using user-specific resources cached in the browser). It only makes the desirable use cases for cookies harder to implement.
To tackle the privacy problem technical solutions can only provide a half-baked solution, the real solution must come from the society. If privacy is considered a worthwhile goal then laws can be passed which will prohibit activities which are considered too privacy-invasive, no matter if they are done with cookies, browser-fingerprinting or whatever technology comes up next.
Still, some technical solutions are possible and are also implemented in some browsers or extensions, like blocking most cross-site cookies. These solutions will probably work as long as the majority of users does not use them. If these techniques are too much in use another tracking technology will be used - as long as tracking is still considered legal.