Here's why:
* Maintaining the mystery: The books are written in a unique style, often addressing the reader directly and emphasizing the grim nature of the Baudelaire orphans' misfortunes. Using a pen name helps maintain this element of mystery and allows the reader to focus solely on the story and the narrative voice.
* Distancing himself from the dark themes: The stories are full of tragedy and dark humor. Using a pen name provides a buffer between Handler and the potentially controversial aspects of the books.
* Preserving the integrity of the narrator: Lemony Snicket's voice is distinct and unique. Using his real name could undermine the character and blur the lines between reality and fiction.
Essentially, Daniel Handler chose to use a pen name to create a more engaging and immersive reading experience for his audience.