I know I'm kind of new to these boards, having only peeked in a little here and there, but I kind of saw the mirror universe lesbians/bisexuals differently. Being a heterosexual, I may be too willing to pass this off, but this is my take:
The Intendant:
Yes, she was bisexual but she was first and foremost a hedonist. The impression I had of her character was that she was out for her own pleasure at all costs. The sexuality issue was simply a way of demonstrating her broad appetites. (I admit, though, that bisexuality is often portrayed as a lack of self-control rather than a sexual identity, as if bisexuals are simply so promiscuous that they don't mind in whose bed they end up.)
Mirror Ezri:
She came across as a woman who was loyal to her friends. She was faithful to The Intendant until the Intendant betrayed her by killing Mirror Rom and plotting against her. I felt that overall she was portrayed as a positive lesbian, who ultimately did the right thing even though she began the episode as misguided.
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I would say that, at worst, the Trek writers were furtive with how they dealt with the issue. They trod a very fine line of public acceptance and, like it or not, they were dealing with the fortunes of a show that cost $1.5M per episode, roughly, to produce. In a commercial atmosphere, it must have been very difficult to try to tackle the issues of human sexuality without alienating the sponsors.
Heck, I'd have to say that they were much nicer with the females of the MU than the males. Bashir, Cisco, and Worf were buffoons while the heavy lifting was pretty much handled by O'Brien and to a lesser degree Jennifer. (Dax and Odo were almost peripheral to the cause.) As to why there weren't more male homosexual couplings, I'd have to say that it's probably justified paranoia on the part of the writers. Face it, the audience for Trek is mostly male. Males are more often LESS comfortable with male homosexuality than they are with female homosexuality. So creating lesbian characters would, in all likelihood (as far as the writers were concerned) be more acceptable to their audience.
Again, as a heterosexual I probably give the writers too much credit, but I tended to walk away from the MU episodes simply disliking the Intendant for Visitor's hammy performance rather than any overt sexual overtones.
