I suppose this is another minor issue that I have with the game, where character-defining traits are spread out over distinctions, specialties, and power sets. And what goes where? It defies my nerdy need to categorize everything into boxes.

With seduction, I would probably say that's covered by Psych or Covert, and can get a boost from distinctions if it's important to the character (and I'm surprised Tigra doesn't have some kind of flirty distinction). Leadership I think is covered adequately by Psych.
I think it's a bad idea to add
too many new specialties, because every new one that intrudes onto the territory of an existing specialty makes the existing one "smaller", and would necessitate fixing existing datafiles. For example, who with Tech specialty wouldn't also have a Mecanical/Repair specialty? And given that, why have the Mech/Repair one at all? So the challenge, I think, is to find genuine holes in the current coverage.
I also don't think there needs to be a specialty to everything under the sun. As I mentioned earlier, it seems like the design puts some concepts into distinctions instead, although where the line is drawn I'm not sure. I can see a need for a Naturalist/Savage/Survival/Hunting specialty (not sure what to call it) for characters like Kraven or Ka-Zar, but maybe they would just have an appropriate distinction.