Sometimes you may want to write with an entirely different personality, a bit different from what people know you as. And its a pain to create and manage a different profile just for that. The option of having a pen name comes handy in that case. So pen name provides you a completely different profile without a need to create a different profile on WriterBabu. You can log in to your original profile and then easily switch between your pen profile and original profile for writing.
Many great authors have used pen profile to see how people react to their writings when they don't know that it is the same famous author has written it. Maybe to get unbiased reactions. Here on WriterBabu, the opinion is generally unbiased but writing anonymously you may miss out on the credit for your writing. Pen names will be useful in that case. Pen names is another way to stay anonymous and have a parallel identity at the same time.