Your job as a UX Designer is to tap into the mind of the user, among many other things, and create a product that compels them to stick around. And this can be greatly improved by creating copy that speaks to them directly, and in the correct voice.
Great design, and usability might keep a user entertained for a time, but without the right copy to get your message across you could easily lose the race to convert them into buyers or subscribers.
Copywriting to a respectable level is not a mountain to climb, its just a case of taking a top-down view of the information you already have for your customer, or product and then putting that into words in the best way possible.
Thanks for reading the article,