Communication is important, otherwise the rest of the community will be left in gthe dark, but they also need a passion for the art form, otherwise what is the point of them being a GM? They should show their passion of art.
I voted "to have a passion for their art form" because if you are not passionate about the art form how could you present it? And i don't think that you would be able to make others curious about it, if you don't really love it
But i also think that communication is important, because if you don't talk to the community you won't know what's going on and you won't be a real part of it!
To be as professional as possible, and be able to think outside the box (prerequisite IMHO) in order to do what's best for the gallery. I'll explain it a little.
I see a Gallery Moeratord as a President for the art form in question. Obviously, you have your own opinion and preferences, but you must have the ability to look at things from multiple angles, rather than just your own perspective. Along with this goes stuff like communication skills, community involvement, etc.