Hmmm... I chose "other aspect of Japanese culture", though it's not entirely accurate.
I'd certainly love to be able to understand Jrock lyrics, raw animes, etc, just by listening. But more than that, I HAVE to take a language in college. I've already had 4 years of German, and I'm kind of sick of it. So when I get to college, I want to take Japanese. It's a language I'm already somewhat familar with (it's the only language I hear on a constant basis other than English, and so also would be the only language I'd have a reason to want to know), I find it amazingly interesting and intricate, and I just love the way it sounds.
So, yeah. A little bit of not wanting to wait for/hunt down trnaslations. A little bit of wanting to understand the music better. But more or less, for aesthetic reasons.