But then maybe that's generalizing a bit too much. I mean, I don't know what kinds of games you play. But I honestly can't imagine someone who's a fan of Japanese RPGs being interested in an RPG which has great gameplay with as I mentioned, terrible, annoying characters and an unengaging plot. Story is probably one of the most important factors in an RPG, as long as the gameplay isn't so bad it's outright tedious.
Whereas, with certain games, or genres, such as puzzle games, of course the puzzle factor has to be fun, and rarely do any puzzle games have a storyline, nor do they need one. So it really is about the genre. Sometimes you just want to scratch your noodle, or kill stuff, and there are certain genres that are designed just for that.
But personally, even for a game with a storyline where I mainly care about the gameplay, like inFamous, or Batman Arkham games, if such a game had a terrible storyline, I'd see no point in playing it. The storyline doesn't have to have the most character development or anything, but it should at least be okay. The characters and the world at least have to make sense in the context of the gameplay. If I'm completely uninterested in the story, like let's say the past several Resident Evil titles, no matter how fun, I'm absolutely not interested in playing them.