Seondeok is a culture+science leader.
Sejong, if implemented, could have not been anything than a science+culture leader (creating a new alphabet for his people? That's the epitome of science+culture).
Based upon our resident Korean, Korean people kept asking for Sejong, i.e. they kept asking for a culture+science leader for a civilization that already had a culture+science leaders.
Firaxis implements Sejong as a culture+science leader.
Koreans are upset because Korea got a second culture+science leader... that they asked for.
I mean, from my point of view, Koreans got exactly what they asked for: a new culture+science leader for their civ that already had a culture+science leader.
I mean, I'm French. For the first years, we were "cursed" with a leader that wasn't even from our country and barely spoke French, with an ability that was, at best, "meh", with the second worst unique infrastructure, and a CUA that, while kind of powerful, is also very passive and limited, while still being yet-another-time-shoehorned into "The Culture Civ TM". We had to wait for the Magnificent persona to get an OK-ish leader, but while the rest of the ability staid subpar. Only with Freleanor we got some sort of unique gameplay. It was for a longer time, and France is still a less engaging civ than Korea. And yet, we didn't got a tenth of the rage and uproar we got from Koreans about it.
Or the Dutch? I'm part Dutch too, and Wilhelmina is the contender with Robert the Bruce for "Most Useless Leader". Good: for my heritages, I have the most useless infrastructure and the most useless leader. Wonderful, truly. Thank God that Spain and Hungary are well-designed, in a sense.
It was already exhausting to have our resident Korean to make a comment every other two comments in absolutely every thread about the leader pass, and now he created his own thread to complain how much Firaxis is on a personal vendetta against his entire country? Why, does he think that we didn't heard him the two thousands and thirty previous times? I know we're fanatics, but isn't there a limit? Frankly, sometimes, I went on a thread, quite happy to talk with my fellow fanatics, and I had blood rushing through my ears because, instead of having nice discussions about how leaders waved their arms, I just had three comments, before even getting to anything interesting, from our resident Korean on how Firaxis has just decided to insult voluntarily his nation, his people, his ancestors and his cat. I'm quite frankly tired of this. One person managed to make me come on the forums with a sense of dread, knowing that every thread will be filled to the brim with our resident Korean whining about how Firaxis made their personal mission to spit on the face on Korea. And I fear when the next three leaders will be announced, because I feel that our resident Korean will have the gal to come and comment: "Why did Firaxis made Elizabeth so cool while they butcher my beloved Sejong???"