The top thing I hope to never every see again in any game is a skill dedicated to flirting, this includes seduction . There are many reasons, from the simplistic to the fact its misogynistic.
Flirting is, usually, explained as a skill to manipulate people who find you sexually attractive.
So lets get one thing out of the way. Communication is pretty much communication, and if you are adept at manipulation you are adept at manipulation. The building blocks of flirting are the same as any type of communication. Also the idea of flirting, like most communication, is culturally dependent. Even two western countries, like the US and France, have very very different ideas of what is flirting.
So, flirting is a communication style, or a set of tools used for a specific purpose. By prejudicing it as its own skill, especially when other major modes or styles of communication are lumped into one skill (or don’t even get mentioned in a skill) your putting flirting on unequal status. And unless your playing a game where every specialty and subset gets its own skill you probably shouldn’t do that to flirting. If your skill system isn’t granular enough to separate radio astronomy from Infrared astronomy than it probably isn’t granular enough to separate flirting from manipulation (or whatever you call it).
I’ve often heard from people “But character X flirts all the time, how would you explain them.” Since I play a lot of spy rpgs that's usually “What about James bond.” The easiest answer, after I stop laughing, is that James Bond just as easily manipulates men around him as he does women. Its just that the tropes are he later shoots the guy and sleeps with the woman. Doubt me? Watch the first 15 minutes of Goldfinger and lets talk.
And then, quite frankly, flirting as its depicted in most rpgs is misogynistic and displays quite a bit of cynicism towards relationships that I just don’t want to be associated with. Flirting in itself can be fine, but in rpgs there is so much baggage that its a bad idea and just reinforces some already bad trends in this hobby.