I think in time, everyone's story will be filled out. This is a trilogy, so the thought is it is one long story. I certainly have hope that the gaps will be filled in, which is why the open questions TFA left didn't seem to bother me, just excite me for VIII.
I feel like this movie is being given a pass on skimmed-over characters, missing back-story, and unnecessary mysteries that any other movie wouldn't. The movie itself feels like a trailer for the rest of the trilogy, and just because they might fill it in later doesn't make
this movie any better. I can't think of a first-entry in a trilogy that did a poorer job establishing itself for it's sequels. I have faith in Rian Johnson, but I'm worried he's going to have to spend half his movie covering stuff that should have already been covered.
Poe is a pretty great character. I can't imagine the writer of Brick and The Brothers Bloom not giving him a large part in the next two movies. Saw an interesting article a few weeks back speculating that Dameron might be gay, which would also be a really cool thing to do. If nothing else, Rey and Finn have been spectacular forces for good in the pop culture universe, and maybe this later development would continue the trend.
I think it would depend on how they play it. To me, if he is gay just to be gay, I don't like it, a la Dumbledore in Harry Potter. If it has no relevancy to the plot, then it feels like its being progressive just so it can claim to be progressive. If depth is added to such a revelation, such that it gives us further insight into the character fast superficially knowing his sexuality, or furthers the plot in some way, then I would be for it, of course.
I agree that it's a question of execution, but I don't agree that it needs to be a plot-point or revelation. Both could be done poorly but I think it's okay for people just to be gay without it being a big deal (just like in real life!).