Why are there different titles for different members?

In any real system there is a variance of skills, experience, ability or purpose. Thus to give certain elected  officials or superiors it is only right to have some kind of honorific titles. Specialist areas like Head-chef, Manager of human resources, Accounts manager, Master of the department e.t.c. A list of clear necessary titles and generic ones for each department or field of research.

If there were enough interest a system of honorific suffixes such as used in Japan (-sama, -san, -domo) is a possible method showing appropriate deferment to someone’s ability, experience or station. Even in the most democratic egalitarian societal systems there must be some form of structure or hierarchy even if only by department.

Finally, considering the academic nature of the community a title could give you understanding of the difference of levels between yourself and a fellow member, much like the kyu, dan belt systems used in a variety of Asian martial arts and sports. The idea of being a 3rd grade black-belt in physics specialising in x, y and z would be an interesting concept.