Nah, I also think its messy RNG coding selecting random text to random picture. I mean it would take more completely unnecessary actual work to determine the sexual preference of the NPC, then segregating the texts into hetero-, les-, gay-, bi-, trans-, queer- compatible buckets and storing them like that. It would also add a good number of tests which would have to be written, and a manual testing everytime a new text is added to see if it isn't offending somehow to the given group... Those things cost real money in development and QA time and that is not cheap. And for what purpose exactly? NPCs are disposables actually, and their stories currently add nothing to their capabilities. Unless that changes I see really little reason for it being an actual design decision and not a plain bug. They just didn't see it (or didn't care) while designing the feature, as well as NPC character creator was often mixing male and female characteristics:
See? Bug.
Why do you assume that's a bug?