Are you being serious? Did you even give the game a chance? That's Kefka, he's one of Gestahl's generals, of which there are three, which has been well established at the point you were in the game. Celes is another one, but you might not know who I'm talking about. The third has made a quick appearance twice.
You understand that at your point in the game, the villain is the Gestahl, Emperor Gestahl, I'd hope. Kefka works for him. Of course, the first hero you meet, Lucca, never regained her memory, either, and the mystery of that creature that you defended at Narshe hadn't even been solved then. Have you been reading the dialog? Are you having difficulty comprehending it? At every point in the game you've played through, including Narshe, it was clear there was more to the story than one more quick fight and an ending, much more to the story, really. Oh, and much more to the character development, too. If you had given the game a fair chance, I'd give you no grief about it, but if you felt like there were several climaxes in the game and that defeating the general, Kefka, would end it at that point, you must not have been paying attention.
Or, perhaps you read some spoilers and learned that Kefka becomes the final boss, but at this point in the game, other than the behaviors and insanity Kefka shows, it's clear he's not the main one the Returners and your characters are after. If you're basing your decision presuming you already know the story of the game, it's clear you are not entirely informed, too.
Were you able to follow FFIV's plot alright? You said you loved it, but didn't the "false climaxes" throw you off there, too?