It's relevant for at least two reasons, in my opinion. The first is that video games, like novels, are stories told through the the protagonist/s. If this character is always male, you miss out on a whole class of stories which are women's stories. Just as literature rarely told women's stories upon a time, video games up to the present time rarely tell women's stories.

The second reason is that having a female protagonist changes the entire meaning of the story. Consider Pierre Menard, author of Quixote (https://en.m.wikipedia.org/wiki/Pierre_Menard,_Author_of_the...), which discusses how the particular context of the author effects the meaning of the work.

Wikipedia had an excellent article about gender representation in video games https://en.m.wikipedia.org/wiki/Gender_representation_in_vid... . One part of the article notes:

> 60% of girls but only 39% of boys preferred to play a character of their own gender, and 28% of girls as opposed to 20% of boys said that they were more likely to play a game based on the character's gender.

So it may not matter to some people, but it matters greatly to others.