When a compound adjective precedes a noun it is describing, we often need a hyphen:
prize-winning recipe, twentieth-century literature. If a compound adjective comprises more than two words, we use as many hyphens as are needed:
a three-day-old newspaper, a dyed-in-the-wool snob.

But try to punctuate the compound adjectives in these phrases: a New York based artist,
a Charles Dickens inspired author,
a post World War II novel. Most writers would take pains to avoid “New-York-based artist,”
“Charles-Dickens-inspired author,” and
“post-World-War-II novel.” Hyphenating open compounds like New York, Charles Dickens,
and World War II feels wrong and looks weird.

Most of us would write New York-based artist,
Charles Dickens-inspired author, and
post-World War II novel. We would respect the integrity of the compound proper noun, recognizing that a hyphen intrusion would not assist readers, and might confuse and distract them.

Some time ago, publishers decided that a hyphen was too puny to join open compounds to other words in a compound adjective. So they replaced the hyphen with the en dash, which is longer than a hyphen but shorter than a long dash. Here are en dashes in action:
New York–based artist,
Charles Dickens–inspired author,
post–World War II novel.

Most books and many magazines would pick the en dash over the hyphen in those three examples. The en dash is used for other purposes too. But you won’t find this mark in most daily newspapers—there is no mention of the en dash anywhere in the Associated Press’s influential stylebook for journalists. In fact, the most respected reference books and style guides of the twentieth century give short shrift to the en dash. H.W. Fowler’s Modern English Usage does not acknowledge its existence. Neither does Theodore M. Bernstein’s The Careful Writer. Wilson Follett’s Modern American Usage gives the en dash two sentences, and discourages its use.

Before the age of computers, only professional printers could make en dashes; everyone else muddled through with hyphens. Many people have never heard of en dashes, despite having seen them a thousand times. The irony is that although the en dash mostly goes unnoticed, its function is cosmetic. It resolves no ambiguities. It clears up no confusion. It does nothing that a hyphen can’t do and hasn’t done, except to look a bit more symmetrical in certain constructions. It is an elegant flourish that most readers haven’t been trained to recognize, let alone benefit from.

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