I think that it is important to understand and study all of the facets of film. One thing I have come to understand lately is that it is generally important to control your representation. In historical films, there were many things that were mis-represented. Films had very stereotypical characters, much so that the protagonist was nearly always the white male. Male roles with other nationalities were either seen as villains, or characters that essentially didn't matter to the evolution of the story. Woman simply could not be the protagonists, and as Mulvey states in her article about the gaze, that women were basically used by the male viewer, and even the male characters. They were, in Classical cinema, considered 'eye candy' for the viewer. Although this has generally changed in the past decades leading up to present filmmaking, it is still important for women to be able to control their representation.
In feminist media, I think the key argument to be made is that it is important for feminists to be able to control and censor their representations. When they are in positions of power, women are capable of presenting themselves the way they want to be seen. They then can be accountable for the representations in film and other sources of media. Women are then allowed to censor themselves, and eventually tell the stories the way they want them to be told. Because of this, women in writing, directing, producing, editing, and other fields of media are important because they are in a position to control this. That seems to be my understanding of feminist media, or at least an important aspect of its importance.