For me its a personal thing. Im a social creature so I like for people to be able to see me as a person behind the posts (my normal avatar is this:
)
Its so people can link the words, thoughts, and emotions to the person, and give it a face, rather than a mysterious nick.
Some people like it that way, some dont. We all do it our how we like it.
On the other hand, is it weird for you to use someone elses name and picture who is more famous in order to get name recognition? Seems like another side of the same coin to me...