I've read Takei's response and he doesn't like it. He actually wanted them to make a new character that can be gay, not gay his character for this.
My personal opinion is open mindedness but also to be creative when it comes to works for fiction. They didn't magically made the entire cast even less white for the sake of diversity. It was already there. Changing an iconic character to be gay for the sake of pandering is not the right way to go. Now I agree with Takei. Make a character that is gay but ONLY if the story requires attention be drawn to it. If the story doesn't involve the gay person liking the same sex like presenting us with a same sex couple or bring it up in conversation, than it is distracting. It's the same with in the future nobody cares about races. They stopped caring about blacks, whites, Asians, etc and it was never really brought up because there is no racism in the human race of Star Trek...shouldn't the same apply to gays of the future in this story? If the story doesn't bring it up...then why bother?
I remember an episode of DS9 where Dax was confronted with her previous life when she was a man and had a child through an affair and met the same woman and there were hints she still had romantic feelings despite being a different gender now, showing us the openness of sexual orientation. A previous Trill character in TNG that had Riker temporary accept a Trill who had feelings for Crusher, who ultimately didn't pursue a relationship because the Trill was then put into a body that is same sex with Crusher. People thought it was homophobic, but it didn't seem like the case behind the scenes.
I am opened to having characters that are gay in fiction...but only if it is brought up. If it isn't brought up...why does it matter? If there isn't a story arc about the new Sulu having a same sex relationship then why bother? Other than because George Takei is gay...who has always played straight people throughout his career and has never let it bothered him.