Blog #1: Definition of a trobe? Metaphor? Connection?

Google would define a trope as, "A trope is a rhetorical figure of speech that consists of a play on words, i.e. using a word in a way other than what is considered its literal or normal form. The other major category of figures of speech is the scheme, which involves changing the pattern of words in a sentence" (Google Define:Trope). Google at the same time defines a metaphor as, "In language, a metaphor is a rhetorical trope where a comparison is made between two seemingly unrelated subjects. Typically, a first object is described as being a second object. In this way, the first object can be economically described because implicit and explicit attributes from the second object can be used to fill in the description of the first" (Google Define:Metaphor).

So in all of manipulation of language, why is it necessary? Is it perhaps the most efficent way to convey a message to a person, audience? Is there perhaps a better medium to transpose with?