A while back, my roommate Pete and I had a miniature argument about writing. Pete doesn't like writing very much, which is probably a result of multiple "English" classes trying to shove stuff down his throat over the years. Pete compared writing to the proper attire for an interview: it doesn't matter what you wear, it's all about who you are, what you know and what you can do for the company. Pete's argument was that good writing shouldn't matter, since it's all about the content of the document. If you make your point, who cares how it's written, he claimed. While I saw his point of view, half of me thought this was utter hogwash, but I couldn't explain why. Fast-forward a few weeks and I've finally thought of an analogy.
Imagine taking a blob of Play-Dough and squishing it into the shape of a car. Grammar is the element that describes the rules -- e.g., a car has a hood and trunk that are lower than the roof, the car has four wheels. After fooling around for some time, you've got a decently-sculpted car (and grubby fingers). Your creation is easily recognizable as a car. People might even be able to guess the make and model of it, too.
A good writer is someone who can look at your Play-Dough car and say, "Hey, you might want to dig out the wheel wells a bit, so it looks like the tires are independent. Maybe add a spoiler, too." The good writers are those that recognize your car as an art form and can show you how to improve your own. When the good writers squish the dough into little blue car forms, people say, "That's a nice sculpture." People enjoy looking at their nice automobiles. People offer them jobs.
The point: Writing is more than just conveying ideas, it's an art form. If painting was just about conveying ideas, we'd be happy with the stuff that little kids draw.
Alternative argument: I just handed part of a current project to my dad, who is an editor. He and I traded what I view to be the most enjoyable part of writing, which is what I like to call the mind games. Well, that sounds pretty evil, but there's definitely a bit of psychology in it. He pointed out that I was discussing something completely in past tense. I had done this becuase the subject I was talking about happened once. He said something like, "Ah, but the concept your describing is timeless. You want the writing to infer that. Changing the sentence to present tense shows your idea doesn't just apply to what happened then, it can always be applied." I'm not trying to trick the reader, I'm simply wording things to accurately express my point.
Alternate point: Writing is a mind game. Write well enough and your readers will begin to send you $10 bills. Then ten of their friends will send $10 bills. And so on, and so on... (just kidding)