The pseudonym, or non de plume, despite it's historic significance in serving the maligned and protecting professional identities, offers no such meaning to me. I do not have any professional record to hide, nor am I oppressed thanking to fair graces and simple luck. My initiation into the use of pseudonyms came instead from illegal activity and the attraction of fostered egos.
The first pseudonym I used was sprayed in chrome paint on abandoned warehouses and written in sharpie on the tiled walls of pub bathrooms. I enjoyed the expression of personality that demanded no loyalty, that could be denied and omitted without consequence. I enjoyed the sensation of a perceived anonymous attention. Moving through the throws of juvenilia and searching, building and at times completely abandoning identity required a rough sort of documentation- a classification of eras, of mindsets and moralities. In a time of life so full with confusion and juxtaposition, being able to create concrete forms of identity offered stability in the ongoing search within oneself.
Pseudonyms allow the artist to express truth, without the concerns of truth's repercussions- this is to a degree cowardly, as truth is partly so important in that it delivers one to all aspects of life: good, and bad, to their full degrees. But in times of cultural suppression, which does more damage to truth than the coward's pseudonym, the hidden identity of the artist allows for works of significant, otherwise unheard voices to be aired in the public's courtyard. Louis Ferdinand Auguste Destouches, a practicing physician of 1930's Paris, cannot publish a novel of youthful aberration without risk to his profession, but Louis-Ferdinand Celine may write openly of military cowardice, of prostitutes and the insane, all in the working man's dialect. William Lee tells of his romps as a homosexual heroin addict in 1950's United States where William Burroughs could yet not. Within anonymity, the artist is safe and responsible then only to themselves and their truth.
There are innumerable reasonings an author might make for their use and choice of pseudonym- they may feel the need to Anglicise their name to Dylan to avoid the antisemitism that Zimmerman might prompt, or to protect their wealthy families name from their experiences of dire poverty like Orwell. (lesser known as Eric Blair..) Samuel Clemens might have decided that Mark Twain sounded stronger, or more American maybe. Or, like the Bronte sisters, they may need to use masculine identities just to be published, in a time when women were not allowed to print. Regardless of reasoning, the use of the non de plume builds in and of itself deeper culture around the artist. Japanese poets who wrote haiku, often would assume haigo ((translating to 'mark')). Traditionally ukiyo-e artists would receive their first go from their school's master, bearing their teachers mark until they entered new spaces of identity, where they would then take on emerging go, symbolising the start of a new beginning, such as Matsuo Chuemon Munefusa's adaptation of the name Basho. The web of Japanese art can be linked together with these shared marks, building a larger stage of cultural history.
At times, the identity of the artist presenting their work is just as important as the work itself. In the 20th century this was exemplified by the rise of rockstars- artists created hyperinflated egos to embody the myths surrounding the body of work and the artists thereof. Those who understood this best cultivated identities of god-like stature. Bowie (who did this repeatedly throughout his career, building characters and their soundtracks simultaneously) and Led Zeppelin, who understood the power of imagery and symbolism, imitating the symbols of the Old-World and the occult to a before then unseen success. While the image cannot stand without the foundations of great work, great work may rely upon the image to draw in it's audience. Ego, identity, character, all rely upon distinction- without boundaries these concepts are lost to the void. Pseudonyms provide the distinction an artist may seek to form shape from the chaos, and rise above the limitations of their environment.