Reason #15: You're a Cliché Abuser

Clichés are the cancer of fiction. They may be hard to spot at first -- a borrowed phrase here, a stock character there -- but if left unchecked, they can metastasize throughout your prose, infecting any shreds of originality and talent, until your output is nothing but puerile dross. See, it's happening already.  

(I'm assuming you know what a cliché is, and not just because people keep saying your writing is full of them, and that your life as an unsuccessful writer basically is one. If you don't know what a cliché is, then it's time to hitch a ride on the Stop Writing Express to Acceptance, where you can catch a bus back to Reality.)

Here's an important point to remember:

Cliché is the plagiarising of what has already been plagiarised

Every cliché begins with an act of plagiarism -- for an idea to be overused, it must be used by one writer and 're-used' by another, then another and another. The idea becomes a cliché when it has been copied so many times that no-one remembers the original text -- or at least, it's been copied so many times that it seems acceptable to copy.

If the original idea was sufficiently broad, and the copying of the idea sufficiently popular, the cliché may be charitably described as "trope" or "convention", or in rare instances, "sub-genre". Which leads us to:

Cliché is a form of fan fiction

One of the (many) arguments against fan fiction is that the fanfic writer relies on the reader's understanding and expectations of the original work, avoiding the difficult work of creating plot, setting and character, and skipping straight to the "action" (often man-on-man, or man-on-wookie). Clichés, especially "genre conventions", function in the same manner, invoking a familiarity in the reader to spare the writer the arduous labour of creating original meaning. Which leads us to:

Cliché is the antidote to originality

Unless you're specifically setting out to plagiarise, or create genre-fanfic, you use clichés when you're just too lazy to think of something original. Not sure what your character would say in a given situation? Or how to move the story from point A to point B? Or how to describe a particular setting, or action, or emotion? Then fall back on your internal database of What Other Writers Have Done™, and hide your shame with the Everyone Does It™ defense.

If you string enough clichés together, you can reduce the amount of work you have to do yourself to little more than typing.