One of the main functions of language is communication, and for this it no doubt helps to be as clear, concise and straightforward as one can possibly be. Clear and straightforward art using language, however, is usually pretty boring. Poets of all stripes depend on ambiguity to impart a richness to the things they write. Words are chosen for their ability to resonate on several levels at once, specifically because they can have multiple meanings in linguistic or historical contexts. This quality, the exact opposite of what you want when trying to communicate a message in everyday life, is one of the things to truly value in linguistic art.
A good candidate for the master of late 20th-century wordplay, capitalizing on all the intricacies and confusion to be found in English is composer/lyricist Stephen Sondheim. A fan of the intricate rhyme, he also rarely misses a pun opportunity when it is appropriate. "I'm Still Here," a chronicle of an actress's tribulations in the business as she is tossed from job to job, contains the line "Then you career from career to career." Career the noun is familiar, but career is also a verb that means to run at full speed. Even if you don't know the particular verb, Sondheim is betting that his meaning will be communicated (career's resemblance to the similar careen may help with this) as will the charm of attempting such high wire punning in the first place.
Sondheim's greatest pun run may come at the end of Act One of Sweeney Todd, The Demon Barber of Fleet Street, in a number called "A Little Priest." Having decided to kill everyone who comes in for a shave and bake them into meat pies, Todd and Mrs. Lovett, the pie shop proprietress, discuss all the kinds of people they'll be serving to the people they'll be serving. Here is part of a much longer discussion, where they talk about the people in terms of profession:
Lovett: Now then, this might be a little bit stringy. But then of course it's fiddle player.
Todd: No, this isn't fiddle player, it's a piccolo player.
Lovett: How can you tell?
Todd: It's piping hot!
Lovett: Then blow on it first!
Here the different realms of the homonyms are explored fully. Meat can be stringy, although you'd never call a fiddle that, but it is enough to evoke a stringed instrument. The ball in Todd's court, he capitalizes on the words that surround the wind instruments. All of this is potentially very convoluted. It is not confusion that reigns, however, but the wit of the characters as they engage in a game of oneupsmanship based on the fact that words can have two meanings and things can get joyously mixed together.
Beyond simple punning, ambiguity can be put to the service of great poetry, so that two things can be said at once using the same words. Shakespeare is often characterized as verbose, constantly using flowery language to say what is easier said in fewer words with fewer metaphors. It's Shakespeare's economy of language, his careful consideration of individual words and his ability to expertly turn a phrase, that enables him to say so much using so little. In King Lear, Act II Scene 4, Lear is asked why he needs attendants at all, and he replies:
O, reason not the need! Our basest beggars.
Are in the poorest thing superfluous.
Lear indicates here that even the poorest have things they do not technically speaking need, things that could be taken away from them. There is also, however, the sense that the poor have too much poverty — they have an abundance of "the poorest thing." This is not a mere pun, but an entire phrase with two deeply resonant, deeply relevant meanings for Lear's plight and the play as a whole. This phrase is a clear example of Shakespeare using the muddled tools the language gives him to profound ends. Out of unorganized raw materials Shakespeare again and again forges a double-edged sword of meaning.
Language is an amazing communication tool. It is important not to lose sight, however, of its other uses. Flights of fancy, low punning or high art, these are all other uses of language that tend make different use of the tools of language than pure communication does. A language designed purely for communication would have no homonyms- they exists just to confuse- and arguably no synonyms-why have two words for something when you could pack all the meaning into one? Just as we praise clarity and concision in language, we should celebrate the impractical side of language and all it gives rise to.