Why did Washington Irving use pen-names?

What is a psuedonym? http://dictionary.reference.com/browse/pseudonym defines it as a fictitious name used by an author to conceal his or her identity; pen name. This is what Washington Irving used when writing his short stories. According to http://classiclit.about.com/cs/profileswriters/p/aa_wirving.htm Washington Irving was born April 3, 1783 in New York City, and was the eleventh child to William and Sarah. His most famous works were "Rip Van Winkle" and "The Legend of Sleepy Hollow." However, Irving did not use his real name as the author, which sparked my question. Why did Washington Irving use pen-names for his short stories? Irving used names like Dietrich Knickerbocker, Jonathan Oldstyle, and Geoffrey Crayon. I did not actually find a logical answer online for this, but I have some theories. I believe that he used these names in order to make the stories more interesting. I mean, who would rather read a story by Washington Irving than some random person named Dietrich Knickerbocker or Geoffrey Crayon? This way, Irving could read his own works and listen to how others reacted about the stories since they did not actually know who wrote them.