Any writer who uses a pen name can tell you there are numerous reasons for using one, three of those reasons seeming to be key. These three are, genre change, to hide your identity, and your name is so common that there are at least 10 other authors with the same name.
There are two classic examples of the genre change. Of course Stephen King. He had already established himself as a horror writer, but when he wrote more mainstream he used the name Richard Bachman. Who could forget about Nora Roberts. Her romance is written under Nora Roberts, which is actually short for Eleanor Robertson, but when she started writing future murder mysteries, she used her sons’ initials and shortened her last name, to end up with J.D. Robb. The biggest reason seems to be that when they switch over they want their new direction to stand on it’s own with out relying on the success of another genre.
The main reason someone would use a pen name to hide their identity is for safety when what they write can seriously offend or expose a group that can do physical harm, and yes that problem does exist. Look up the undesirable journalist.
Of course who can forget the problem of multiple authors with the same name. Unless you are a bad writer you don’t want your writing to gain popularity on someone else’s established name and talent, so you use a pen name.
Whether you use a pen name or not is up to you, but you should have a reason for it. No, because it’s cool, is not a good reason, but proceed with caution when you pick one. When you establish your writing, your pen name will go with it, and who wants to read a serious novel by a name like Henry Pinklestein.
Challenge: If you decided to use a pen name, decide how you would choose one, and think of one you think people would go to in your genre.