Gaila's importance has been elevated in fanfic for a few reasons, but one big one is that she's extraordinarily useful. Arguably the biggest ship in STXI is Uhura/Spock, and since fandom loves the first times and beginning relationships, there's going to be a lot of Uhura getting to know Spock. Spock, however, is a very closed person. Uhura is not going to jump right into heart-to-heart stuff right away. She will be frustrated. So she will need someone to talk to. That's Gaila.
Hmmm. Very minor character in film elevated to major supporting role in fanfic, in large part because she offers a way to get at the feelings of major film character who is romantically interested in emotionally distant male lead. Why does that seem --
Yup. It's X-MEN movieverse all over again. Gaila is Jubilee.
I mean, the fic is better, but Gaila's promotion partially involves a similar dynamic, and that amuses me.
(* Amusing footnote: I was rummaging in my archives recently and happened across a ten-year-old Usenet post in which I argued very cogently that the ratio of porn to gen in a fandom's fic was a barometer of the quality of the original material: i.e., if the original is good, fans try to emulate it; if it is crappy, their attention wanders and they do stuff that's radically different, like, oh, say, porn. I don't know if I was as right then as I thought I was -- it would sound bizarre to say something like that today, but younger fen should realize that ten years ago the level of sexually-oriented fanfic was way, way, WAY below the amount now -- but even if I was dead-on in 1999, that sure isn't true anymore, because large numbers of folks are very specifically here for the porn. Case in point: the folks writing STXI are turning out lots and lots of fic, lots of really good gen fic, even -- and what was the first big explosion of fannish creativity in that fandom? The kink meme. People came out of the theater and went straight home to write the porn! (That a gen meme followed, I think, says very good things about that fandom. It is not my fandom, and I don't think it is likely to become so, but it looks like it's going to be a positive influence on a hell of a lot of up-and-coming fan writers. I'd much rather neofens cut their teeth in a fandom where there's a healthy mixture of story types and character interactions than in, say, McShep.)