Companies like to make money. Cell phone makers do it by selling phones. By always having something newer and better they create more demand than if they only sell the same old thing, even if it was good enough. This way, they encourage people to buy phones before their old one is broken or out of service simply because they believe they are getting something better. If they just let people believe last year’s model is still good enough, fewer people will decide they need to upgrade and they won’t sell as many.