Most people have already answered the question from their perspectives. The only advice I have is that education is useful for different things but it can be much more rewarding if you specifically know what you want. There are certain areas of publishing that requires a specific type of writing, which may be easier to achieve if you already have certification with an association, or a degree, to back up what you are writing to be more legitimate. That does not mean one requires the other in order to do the other, there's not one single path for all. There's always the possibility that the individual just wants the experience alone, which is also valid so I don't think any less of those who get a degree in History for example. A degree in History can be applied to many fields or careers and could be useful, but not everyone's path or opportunities are the same so there is no certainty for any degree. The only certainty you can get out of a degree is how much work you devote to it, and the choices you make.
I chose chemistry because I've had a love of the environment for over a decade, and I was interested in a scientific field that was connected to others where I could learn to use instrumentation. Hence, "Chemistry" is a central science, where other disciplines overlap with it. The reason why it's useful to have a Chemistry degree or any field in science is access to laboratories, equipment, and other researchers. You gain support from all of it as a community. Alternatively, you could learn Chemistry on your own, but it would cost a substantial amount of money to build a laboratory and convince the DEA you aren't a drug manufacturer. And well, if you want to do writing for Chemistry or some other fields, you'll need access to those laboratories in order to research topics to write about that are publishable. In many science fields the the mantra is, "Publish or Sink" because you need to do research and become published in order to prove yourself.
The only way to answer the original question is whether it's useful for the individual, and what type of writing you ultimately want to do. For creative writing, it may not make a substantial difference, but you will gain something else out of it than just learning how to write better. You may gain new connections, meet people, learn about new ideas, and you will have a degree. Whether the degree is useful to you or not, that is a difficult question to ask but honestly only you can find that out. It takes soul searching, and a lot of thinking. Ask more people for advice, and seek out a community college adviser. If you can pinpoint a specific career you want from it or a goal, great you should ask others how they did that, but not everyone wants a career. Some may only want the experience by itself which is also good. You do not a degree to do any writing ultimately, there are some areas where you could teach yourself and save money. I work in an Advising and Counseling department at a college. Everyone who comes through those doors either knows what they want to do, or alternatively they have no idea at all. It all depends on many factors, whether you gain more from doing one alternatively to another.