Good question Patti. Here's a hypothetical..
Let's say you discover a need in the writing market. It's on the subject matter of needing more info on the fruit selection process. You title the book, "How To Pick Fruit". The book shows you the ins and outs of picking the best fruits with researched data on the best time to buy certain fruits, and the best regions to get them based on how they are shipped.
You talk to over 50 scientists, 50 fruit workers, and research the subject from various books. After you compile all this research, you realize that you don't want to be known as the expert on Fruit Picking. You simply were trying to help out the market, thought it was an interesting topic that may sell, and wanted to just do it. You felt you could make the topic entertaining and also include more data on the nutritious value of fruit. Going into the research, deep down you knew how silly the overall idea is. You also knew that you'd be picked on based on it and that was indeed the major selling point of the book. "Someone wrote a book on fruit picking, look at that, people will do anything for money" people say. But you thought it was interesting and felt to let your sense of humor take control. You think, "Why it could be the definitive guide on fruit picking that every fruit picker in the world is required to read before starting their job". "It could be translated into 100 languages." So you go for it.
So your name is Scott Bobarrel, instead you put on the title, Michael Apple or Steve Applebaum.
The reason you do this is because you currently work in an industry that you wish to publish more serious books on. You may be a doctor, a Lawyer, an Investment Banker, or a CEO. Rather than put out this book and associate with your other non-fiction titles that you know you will eventually write, you instead put it out under a pen name.
That's just my long drawn out analogy. Again, that subject, feel free to use it if you like! As I am sure there is a market need for it!