That's true, but it's not the only thing enjoyable about jRPGs. From a storytelling standpoint, you're right. jRPGs are railroaded and therefore if the story's spoiled, there's no point playing for the story anymore. But you can still play for the challenge (and don't say jRPGs are all easier than wRPGs, because there's always Atlus), for the fun, and the sense of accomplishment.The problem with the replayability of JRPG's is the fact that if you know the story already there is nothing to drive you through the game.
but more to perverted basement dwellers.