Writing... is a lot like a stubborn dog.

Let's take a look at that somewhat-used simile that is the title. "...like a stubborn dog." It's a comparison that is, while fairly vivid, also incredibly expected. A true nonsequiteur can, in contrast, be original enough to *seem* creative, while not having any kind of actual meaning. Coming up with a good simile is like hitting a mall Santa over the head with a copy of The Karma Sutra. It's difficult to set up, and by the time you're finished, you find yourself wondering if it was worth it.( Incidentally, if there is anyone out there who just nodded understandingly at that passage, perhaps with the gleam of fond memories in their eyes, then I urge them to either seek medical attention or email me.)

My point here is that the line between profound and artistic is a tricky one to tread, particularly when the vast majority of readers really WANT to feel special and intelligent at havin caught your meaning, but also want to glean something from your writing. Suppose, for instance, you wrote an extensive story about a plumber who finds himself in a search for the true meaning of life, while using plumbing as an extended metaphor. In the end, he has a monumental epiphany, ascends to a higher plane, and gets to hang out and watch Mythbusters with God.
There are a fair number of people that would understand this book deeply, and would look for multiple layers of interpretation in the words, treasuring the philosophy that it presents, because it makes so much SENSE. And *all* of these people will be plumbers.
How many people, do you think, know what a three-eighths Heynman Grommet is, and recognize its significance as a symbol for ultimate human struggle? It's not a very large number, (I am not one of those people either) so using that particular nugget of symbolism in your writing is an uphill battle. Any attempts at conveying something deep in a new, unfamiliar way is going to be lost on the vast majority of people. Any attempts at conveying something deep in a way that has meaning for people in general has already been tried by numerous authors is firmly in the "cliche" category, and is thus untouchable by any truly serious writer.
As a result, it is the writers who have enough lack of awareness of cliche -or lack of shame- to use the symbols, plots, and ideas that make the most money. Twilight, a romance "novel" that is centered around vampires, is something like the 20,000th duplication of the same plot, and has naturally sold over 25 million copies. Do you think Stephanie Meyers regularly pats herself on the back for her groundbreaking plot and characters?
Am I the only one who gets a massive headache whenever I think about this?

Any creative ideas lack enough mass appeal to justify writing about them, any ideas that HAVE that massive appeal are old and smelly and are occasionally lugged out onto a stage so that everyone can throw money at them for a while, before disappearing into the back and never being heard of again. Sometimes a movie is made as well.
The problem here, is that it puts writers who care about anything more than money in a very frustrating place. If everyone is going to be reading Eragon, a book that is essentially "ctrl + a", "ctrl + c", and "ctrl + v" in terms of originality, then why would I try and publish my brilliant breakdown of human suffering? People are too busy pointing and going "Ooh, dragons!" to pay attention to my work. Therefore, I am forced to either sell out, or hope to dear God that someone significant will notice what I'm doing and kick my book into the public eye.

That is why writing is like performing hip surgery with a tennis raqquet. It's hard to do, and even if you succeed, there isn't very much chance that you're going to make any money at it.

--H. P. Pseudonym