There's absolutely room for interesting LGBTQ and minority characters in a mainstream game. For example:

• femboy who happens to be really good at sniping or shanking people
• obese person as your tank or support
• trans (either way) as a ninja or shape shifter (maybe a little on the nose?)

And so on. Make them interesting to play as, and also include some "traditional" characters (hot, scantily clad women, muscular men, etc). Each character should be interesting, visually distinct, competitive to play with, and not too stereotypical.

Games should be fun first and foremost, then interesting, etc. Including minorities is a pretty distant nice to have, so if you're going to do it, make them fun and interesting to play with.