It can be obvious to tell you this, but when you write unintelligible content, your customers will go through a bad user experience. No one wants to enter a website where the text is difficult to read, follow and understand. Besides that, it is boring and perhaps filled with keywords. People who encounter this type of websites won’t click again on it.
When you are planning on writing some content, it should be aimed and focused on your target audience. They are looking for something, and they should get that answer in your website. Likewise, when your text is easy for search engines to understand, it will probably rank higher. Of course, you need to create a balance for the two, to be easy to understand by search engines, and to give a great user experience as well. So, you need to find a way to intertwine both of them in a holistic sense.