When you write to sell, you want the focus to be on the product - not your smooth talking voice.
Imagine a salesperson using poetry to sell you something. Although it would be entertaining, it would not help sell the product.
Don't write to entertain. Don't write to make YOU sound better. Write for THEM.
The problem with academia is it is built around bolstering YOUR ego. In the real world, having a big ego is counterproductive to working your way up the ladder. It's like having a broken leg in a marathon.
Don't believe me? Just look at how much trouble people with degrees are having. They can't find jobs. They don't have social skills. They have big egos, but can't make money.
And yes, I have a degree. I have a piece of paper that I can tell people I have. My clients are only mildly interested in the fact that I have one.
The amount of people that can write at the standard people on HN use for a well thought out comment is low. Very low. This also includes people with degrees. The vast majority of the population are as articulate with written language as your average YouTube poster.
Clearly most people can read a higher standard of writing than they can write themselves, particularly if it is a subject that interests them. If you are expecting a response on a one to one basis, e.g. an email, then writing at the top of your craft really might not be the best thing to do. Your well written feature length English and all of those big words might come across as intimidating. This factor means you may not get a response. Writing something simpler, i.e. to not show off one's mastery of the language might get a better result.
Far too often in academia you have people using big words without really knowing what they mean, as if they are using the thesaurus a little too often. Or they use buzzwords and acronyms when simple English will do. It is as if some people have a false idea of what it is to write properly. They try to impress but fail. They then enter the world of business and try to write the same way, caught up in trying to use big words rather than focusing on a simple message.
So yes, write for THEM. At times, to a wider audience this might mean writing at a level found in a tabloid newspaper, which is okay if done properly.