According to Rod Beattie in his Will Power presentation, studies have been done analyzing the working vocabulary of various poets. What was found was that the higher number of words in the working vocabulary, the more popular the poet. Such luminaries as Keats and other famous poets had working vocabularies ranging between 7,000 and 8,000 words. Shakespeare's working vocabulary was about 28,000 words, or more than three times that of any other poet writing in English.

At the time Shakespeare was writing, the English language was going through explosive changes with many new words coming into the language. Words were coming in from French and Latin and being dug up from historical versions of English words. Shakespeare used words that were coming in from every root.

Improving your vocabulary seems more likely than anything to improve your standing in poetic circles and chances at lasting fame. You still need to communicate with your audience, so just digging up abstruse or obsolete words may not be helpful. However, an expanded vocabulary will allow you to delicately shade meanings and judiciously imply double or triple meanings. A large vocabulary also allows brevity, as you might be able to state something with one word that would take you a sentence to describe. An expanded vocabulary has many advantages for a poet.