The adage states real estate's three most important qualities are location, location, location.
Along those lines, the three most important processes in self-editing are simplify, simplify, simplify (or clarify, clarify, clarify—choose your preferred synonym). And yes, that includes many classic novels on the canon which stumble under the burden of overwriting.
That's in no way to say I believe all reading should be easy—give me a good meaty chunk of writing to gnaw on any day.
The question does not fall into binary results. Something can be complex but clear and succinct, just as something else can be simple but muddled and redundant.
Image: Gettysburg
Consider Abraham Lincoln's famous Gettysburg Address, reproduced in entirety on the Library of Congress site. Clocking in at just ten sentences, the speech is gorgeously written, with specific language, strong nouns and verbs, and total clarity of purpose.
Could the opening have been dumbed down to "Eighty-seven years ago" rather than "Four score and seven years ago?" Sure. But would that edit have enhanced simplicity (or clarity)? Debatable.
What isn't debatable is that generations of United States middle schoolers would not be required to memorize a speech that began in such a flat way. And would any of us name that tune in four notes without the poetic (yet clear) language?