I have run into issues with the FB app because it seems to run so hard and ends up draining my battery. I go back and forth with having the official app installed and just using the web client. It isn't half bad but I liked being able to using the FB app to auth my accounts on different apps. Any there any other reasons to have the Facebook app installed?
If you plan to develop a Game or App and would like to use a "Share to Facebook" function, then having the Facebook app installed is necessary for debugging. Other than that and the reason you mentioned about the authentication, I can not see any other particular benefit of having it installed for Developer related reasons.