The funny part, in some ways, I kind of agree with you. I never expected the game to sell well in the states, not at all. I can understand in Asia, where the 3 Kingdoms story may have more fans and people to relate the game to the books. However, somehow, the story is breaking Western ground and people are coming up with favorite people and stuff. I don't think the game would get any big merit if it wasn't for people getting into the history behind the game. (The rest of them, the casuals, must be getting into it for the sheer ability to finish a round taking on 300+ people with one bad mofo of a general and their bodyguards)
At first, I did wonder myself, as how this would get a look if you have more significant dungeon crawlers with more general gameplay elements like the D&D games (Dark Alliance/Heroes/etc), and such. I, myself, just love the Dungeon crawlers, even ones dressed as big war fields with arcane magic mixed in, but I never thought these games would really take off.
I felt the same as you, when I played Dynasty Warriors. Though I did like the idea of getting on horseback and riding through the field. I was already familiar with the Romance of the 3 Kingdom games since Bandit Kings of China, way back when. But somehow, putting the game and the historical book together, kind of gets you into the characters in the games. I'm not exactly sure how to describe it, but once you get to know the characters, you kind of feel the love of playing as them.
I guess I'm one odd person, I guess. I'm one of the ones that loved the way Romance of the 3 Kingdoms 8 is set up, because you get to play as a character that's related to one of the many characters, in the game, and even get to make new legends of your own. (Wanna play as the Son or Daughter of Lu Bu? Go right ahead! Laugh as your father checks up on you, like some concerned parent, and it's Lu Bu.) The RPG aspect of 8 really puts a big romantic and emotional touch to the series, and I definitely like that. And yes, KOEI is still very good about making strategy games in which Emotions and relations actually are a very important part of the strategy and gameplay. No other company creates games like that. Still, none of their games are for everybody. However, unlike many other Niche games, the ROTK fans are high in number, and ensure good sales. It grabs the hearts of those sympathetic to the chinese and those stories that talk about the strife, that happened, in order to unify it. As Jackie Chan said, himself. Everybody knows about War.