We weren't talking about TNG, we were talking about DS9, which ran from 1993 - 1999, comparing it to shows like Northern Exposure (1990 - 1995), Mad About You (1992 - 1999 [not counting the revival season]) and Friends (1994 - 2004), which would certainly be contemporary.
And "The Golden Girls" (1985-92) which had a same sex episode in season 6 (1991) and had an out character a couple years earlier (Clayton Hollingsworth). Portrayed by Monte Markham, guess which DS9 he guest starred in and as quite a different character too?
"Married with Children", in season 5, had an episode around gay marriage - played by Dan Castellaneta of Homer Simpson fame - and, as with Clayton Hollingsworth, the writers didn't use lame caricaturing* but instead crafted an actual person with some depth -- ditto for the episode when Marcy's cousin visits in season 11. IMHO, those characters I could relate to far more than Captain Jack or many non-hetero people scripted today; it's sad when sitcom characters have more depth and gravitas to them and that's a testament to the scripting and acting. Even "All in the Family"'s first gay character from 1971 (a mid-season replacement show that was given a disclaimer...) was as truly a gutsy move as it was going against a stereotype.
And, usually, if a character isn't gay or straight or shown to be one way or another, or even if mildly hinted at, it's enough for many people to go "Okay, that's a cool character trait and might be important in the show to know, so what else is this character about?" Just as with the straight characters.
* IMHO, that level was used in "Soap", a sitcom from the late-1970s... but in that show, everybody in it was more or less a caricature to begin with.
The sad part is, I've never watched Star Trek for shipping. Most of the time I've laughed at the screen when Kirk runs around teaching "luuuuuuuuuuurve" to the lady of the week as well. It's unintentionally hilarious and if the show didn't have other things going for it, I wouldn't have kept watching. Anyone watching Kirk because he's hetero just seems as silly to me as watching only shows with gay people just because they're gay. YMMV, my ex fiancee only wanted to watch shows revolving around gays because he needed fictional tv shows to validate one aspect of his existence, as if no others had. That and lots of booze and the truest acts of abuse. But plenty of shows exist for everyone and plenty of shows offer more than just one thing - fortunately!