IMO - done right is very important. And I don't think that is possible with only 20 pages dedicated to story telling. Certainly not in a "main" book as it were. The solo would be the only place and it would need more than one issue.
Iceman's coming out was done in FOUR pages. That is it, and horribly written, done between two books that were published months apart. That is two pages per book (it really was two per) and it wasn't even Iceman stating anything, it was forced by Jean Grey who didn't respect his privacy. (Privacy issues aside ... we're not even getting into the "joke - Iceman is gay" thread on CBR, that spurred a writer for the character change).
Iceman's own solo didn't even address his sexuality in any meaningful way. It just rolled on with his status quo and dealt with his "dating". Not sure where the book is now, I dropped it. I'll have to count on others to fill me in more on the book. Edit: the book does or did have the opportunity with his parents, whether dealt with or not. I don't know.
I'm uncertain what benefit the LGBT+ would get from a story of Gambit being bi, his reputation alone would contribute to a stereotype. Even as the hardcore fan can debate his rep, he still has it and may not lend itself in a positive way. IMO.
In the end, doing something for the sake of it, or to get publicity doesn't always benefit the group intended to be represented.
addition:
Not saying a good story wouldn't be possible or done well or any of that - I suppose its my lack of faith in the writing abilities of those who work for Marvel or DC that makes me doubt.
edited to original quote