The franchises have had pretty different attitudes towards gay characters over the years. Gene Roddenberry was very "wink wink nudge nudge" about K/S slash, but George Lucas was super against any mention of slash. I think it's more important to Star Trek's image to have gay characters, since diversity and acceptance is such an important aspect of the franchise. I can also easily imagine Star Wars nerdboys freaking out about gay characters in the movie franchise, whereas everyone seems to be taking the news about Cho's Sulu very well.