My point was that having a black woman be one of the astronauts in the future was inspiring, not they there was merely a black woman in the cast.
My whole point is that her inclusion wasn't driven by plot considerations. So I think it is disingenuous for some to claim that a gay character should only be there if he/she serves the plot.
I agree. I HATE that argument, since characters are straight all the time without it serving the plot. It's a double standard, and clearly meant to limit how often and how gay characters are used. And of course, if the character's orientation does serve the plot, then the haters will complain that there's a gay story.
Diversity should be the norm because it would reflect real life and the audience. What is artificial and off putting is the lack of diversity, how overwhelmingly white, male and straight most shows and movies are. It's all too common, for example, out of a cast of 5 leads to have four men and one woman, who of course is there to be a love interest.