Clearly humanity has found a cure for homosexuality in the future!
But wait... wasn't there some hot female trill on trill action in ds9?
Ohhhh yeah
(and many other quotes along these lines)
I had a feeling this would come up. I tried to emphasise the complete absence of "human" homosexuality in Trek while writing the OP, and the show seemed almost cowardly in is use of "special circumstances" to barely concede even the existence of gay aliens or people.
Consider "The Outcast", which seems to be often cited as an indirect attempt to tackle the subject of homosexuality. Its actually an episode about gender identity, but even then still extremely shallow in that Riker's love interest is definitively female with none of the supposed gender ambiguity the script seems to be referring to. Rather than simply depict homosexual(s) as equal functioning members of Starfleet (in the same way that TOS had unfairly-demonised people of different racial backgrounds on the bridge with no comment), the series attempted to make a point on a subject that it was too afraid to be overt with. At no point is homosexuality addressed in the episode, at all. Riker discovers an alien who identifies as a woman and has a hetrosexual relationship with her.
"Rejoined" wasn't about Jadzia's love for a woman, it was about the asexual Dax symbiote's love for another asexual symbiote. Its another example of a series of "special circumstances" leading to the gif'd woman on woman kiss. Its a cowardly way to directly avoid addressing the subject of gay people.
There were admittedly bisexual and lesbian aliens in the mirror universe, but its played entirely for comedy and/or shock value and titillation, and is again another example of "special circumstances" - in this case the homosexual behaviour is attributed to the cartoonish mirror universe.
The quotes I provided in the OP would seem to suggest that Rick Berman was behind it. Considering the dipshit was behind most of the decisions that killed Trek (and was distant from DS9 incidentally), I don't find it difficult to believe he was a short-sighted figure repressing any attempt to bring up the role of gay humans in Trek.
The consequence is that, as of Trek canon at present, there are apparently no gay people in the twenty-fourth century. Any apparent same-gender kisses, are
always the act of aliens, or possession, or something completely out of the ordinary.