One question many authors are asked is if they would ever write as a pseudonym author. I will ask the question back, why do you think I am not already writing as a pseudonym author? There are fantastic reasons that an author would take on an alias.
To write with a pen name, an author can feel they can let their creative juices flow, without the fear of being judged. It can be hard as a writer to feel like you are bing held back from what you would prefer to write on a page. There is always a story in your mind that is itching to come out, but there is also always a voice in the back of your mind that reminds you that your relatives and/or friends may judge you by what you have written. If an author has to always second guess what they are writing, it can take the fun out of the story telling process.
There is also an issue with your readers not wanting to change the genre of the books they are reading. Many authors who are known to write mystery, but would like to dabble in creating something different, let's say a romance novel, their loyal readers are left confused. It can be wiser for the author to change their pseudonym name with the goal of not annoying their fan base. Can you imagine waiting for a new Stephen King book, to find out that he decided to write a graphic novel? Authors can get pigeonholed into the genre they started their writing career, but have a desire to write something else. With a pen name, they can have a chance to spread their writing wings.
Many authors write as a side job, and have another profession as their day job. The author may not want their boss, patients, clients or co-workers knowing that they had written a genre that wouldn't look good in their line of work. Can you imagine a tuff bodyguard writing children's books? Or finding out that your hairdresser writes horror stories about a serial killer murdering victims with scissors?
For whatever reason, many authors write with a pseudonym name. I currently have not written any books under a different name, but I can't promise that I will not in the future!