I'll be honest, I thought that Sulu's family scene was nicely done and that it felt organic. Sulu is easily one of the strongest characters in the reboot franchise and I think that the subtle incorporation of his sexuality sends nothing but a positive message to the audience.
It's true that the gay component to his character is only briefly touched on, but there's not a whole lot of space in an action movie to do a lot of prolonged character development. I think that taking more time away from the movie to focus on his sexuality or inserting a brand new character into the cast simply to explore the LGBT angle would probably have been seen moreso as tokenism than what they did. Filling the vacancy left by Chekov with an LGBT character would've been a good opportunity perhaps, but of course Anton didn't pass away until after the movie had been filmed, so it's not as though they'd have known that to be a potential possibility at the time. They also probably didn't know whether they would be getting a fourth movie at the time, so they had to decide if they were going to do something now, or if they were going to wait for another opportunity to inject a new character into the franchise that may never have materialized. I personally prefer that this strong, leading character and organic member of the crew was written as being gay, rather than writing in a new character that joins the principal cast three movies into the series as an outsider. This allows us to connect with the character in a new way, as we re-watch the first two movies, realizing now what his family life is.
I totally get that people want to see a fully realized LGBT character in Trek. So do I, and I think that the upcoming series is going to be a great opportunity for that, where there will be ample time to develop and fully flesh out the character. I think that the movie incorporated it nicely and as best as they were able, and that the much awaited attempt at representing the gay community in Trek came from an honest place in their hearts. I don't think that we should be in the least way upset with the Kelvin universe incorporation of an LGBT element through Sulu :)
