I'll bet you can name a handful of authors that you simply ADORE. You buy their books in hardback, watch the bookstores for signings, search amazon.com to find out when the next masterpiece will ship. What makes them so special? Why do you love their work?
I would argue that, in most cases, it's because you like their VOICE. Voice is like an author's fingerprint. It's what makes the writing unique and individual. It's a combination of phrasing, diction, dialogue, character development. It's simply what makes Faulkner Faulkner or Hemingway Hemingway.
Voice is a difficult thing. It seems like it would be an easy task. We're all different, so we should all write differently, right? Unfortunately, it's not always that easy. Sometimes you have to work at finding your voice. You have to play with composition, structure, and all the other elements that make up your work.
Think of it like this: When you bake a cake, you use the standard ingredients: Flour, eggs, oil, baking powder, salt, vanilla extract or cocoa, sugar. But do all cakes taste the same? No---it's the pinch of cinnamon, or the cup of pecans, or the helix of lemon zest that can make all the difference. And why does your wife's pound cake taste so much better than your mother's? (Or maybe it's the other way around at your house. LOL) And even though your mother has given your wife that recipe a dozen times, it never tastes the same, does it? Is it the proportion of the ingredients or the temperature of the stove?
VOICE is your literary fingerprint. It makes your book, or story, or poem special and unique. Sure, it pays to read other authors in your genre, but not so that you can copy their recipe. You should read them in order to expand your thinking, open your creative channels, so that you can create YOUR OWN VOICE. Finding YOUR OWN VOICE will make your characters leap off the page, it will make your settings tangible, and your dialogue snappy. It will also help move your manuscript from the slush pile to the center of Mr. Dreamagent's desk.
When you present your cake to the world, you don't want it to be a Betty Crocker Mix with icing from a plastic canister. You want it to be your recipe---the one you've slaved over, perfected and polished. You want everyone to say,"I LOVE THIS CAKE . IT'S THE BEST CAKE I'VE EVER TASTED!" And you want them to mean it---because it is yours and only yours.