Here are three reasons to consider writing something different, whether you're in a rut or not.
- You might find out you like/are good at what you try. Just like with trying a new food or listening to a new type of music for the first time, you could very well find something that you enjoy doing quite a bit by trying writing something beyond your usual work. Depending on where you are in your writing career, it may or may not make sense to pursue that with vigor, but it can't hurt to know it either way.
- You might be able to take things you learned from the experiment and apply them to your more-typical work. One of the things that you would hopefully be doing from this type of experiment is growing as a writer, at least in breadth of experience. Having broader experience gives you more to draw from while writing in general.
- You have a bit of experience with something new if you want or need to work with it more in the future. Maybe your experiment was with writing a story in a setting different from your usual setting. If a themed anthology opens up, then, which depends on that setting you already have some background knowledge from which to start.
That's a great thing about being a writer -- all this stuff funnels into our brains and it can come out later in pretty darn awesome ways!