The sexuality issue could've been about Spock. A lot of questions about Vulcan sexuality can be explored because of the growing relationship between Spock and Uhura.
Are Vulcans sexual creatures? That is, do Vulcans have sexual feelings towards someone? Pon farr itself may just be an incredible urge to mate for procreation, not a desire to express sexual feelings for the pleasure of it. Bear in mind Vulcans seem a bit embarrassed by pon farr and the feelings it unleashes.
To a Vulcan, can sex be solely for the pleasure of sex? Is it logical? Sex is one of the ultimate emotional experiences. For humans, it can be an essential part of a relationship. But would engaging in it purely for the fun of it and both the emotional bond and release it creates be contradictory to Vulcan stoicism? Do Vulcans even have a libido to be satisfied?
I would think that those questions have to be answered before the relationship between Spock and Uhura can advance beyond simply stealing kisses and caring for each other.