The reason all these UFC level fighters feel the need to comment, in my opinion, is, as you say, because its a pertinent issue. I don't believe that the fighters who have commented believe their comments are so important. They're just commenting on what is the most talked about subject in MMA at the moment.
I guess the main reason I'm so irked by all of this is that no one looks at the caliber of opponent she was facing as a factor of her success. They all form opinions centralizing around her sexual identification.