The consequences of this phenomenon range from amusing to disturbing. In the former category we can place words, names and phrases that almost certainly would never be copied whether protected by copyright or not. Where all this starts to get disturbing is when it encroaches on our freedom to use, not silly slogans, but commonly used words and phrases. Brand X has, for all time, seized the right to call itself the best motor oil. What we have here is a corporation gaining ownership of words that are not even true.
Most advertising slogans are neither true nor false, but unprovable assertions.
Furthermore, facts change. Ford cannot for all time claim to build the world's largest sport utility vehicle, because next year Dodge might build a bigger one. There is certainly a legitimate need for copyrighting and trademarking. People and corporations who do this are hoarders of words. Fearing competition, or maybe having an inflated opinion of their phrases, they want to forever deprive others of the right to use them.