It was more me ranting about stuff than something specific at your post, it just served as a catalyst to me, so sorry if it seemed otherwise. The thing is that it bothers me a little when people say "don't use X", because I don't think this should be said (especially because most of the time, the way it is usually said, passes the idea that it will be actually harmful, instead of not being beneficial if that would be the case). I mean, sure, if you're doing brute force for 6 hours every day because you need to get good by 3 months, of course you have to limit what you use as a material, it's about priorities. But otherwise they are valuable, well, at least I see them that way. I think most of the disagreement comes out from what we want out of learning Japanese, and how we go about it.
I don't plan to move to Japan. I think it's a beautiful country, and it seems like a nice place to live (not so much for working though, from what I've heard). I really want to visit there someday. But much of the entertainment I consume comes from there. They often do stuff that fits right in what I want from media. And I want to know Japanese for that. I like to learn stuff. I also want to learn music theory, get back into practicing guitar, I want to learn how to draw and 3D modelling as well. I'm majoring in Computer Science, but some time down the line I serious might go to collage for Chemistry because I loved the classes so much that it's just something I want to know more about. So I'm in no hurry. I don't want to pass N1, I don't want to get a job there and move. My priorities are reading and listening. The production side of things matters little to me, because as things are now, I have no reason to write/speak. So yeah, "[media] is not natural language", sure, but "thus they are not useful", is were I disagree. They are useful to me. They are useful because of what I'm going to use my jgo knowledge on. Music does matter a lot to me. Matters more to me than being able to speak naturally. And don't get me wrong, I do want to be fluent, I do want to be able to converse naturally if/when I visit Japan. But right now, it's not something that is on my sights. So they way I study is going to be different and have another pace compared to someone who wants to go there ASAP.
Also, another things that make songs useful to me right now is that 2016 is going to be an intense year for me. I basically will halt my Japanese studies. In the morning I have work, in the afternoon, college classes, in the night and weekends, studying and doing school work. But also, this is my last year. I don't know how things work elsewhere, but here I have to do a "TCC", which literally translated would be "Course Completion Work", or a (final) term paper, if I understand that correctly. I have to do a research simultaneously to classes and present it at the end of the year, which will determine if I graduate or not. Even tough I'm in vacation, I'm researching stuff and talking to my advisor to chose a theme so that by February, when classes start again, I already have the theme set and got the basic process down. I won't have time to study anything else. I won't have the energy to study anything else. But if I'm there, listening to music, and I know that I will, I might as well try to get something out of it.
I also don't get why people never enjoy classical Japanese songs, or documentaries, kabuki, or light novels.. why is it always anime, manga, games.. but I digress..
One of the major reasons I want to learn is because I really want to read NisiOisiN novels. Also, it's generally anime/manga/games because they are the most accessible to people outside Japan. There's very little light novels translated, and it's usually fan translated. It's very hard to find (in depth) info about other parts of the culture if you don't already know Japanese.
And this reminds me of another point. Generally when "don't use X" comes around, X usually is anime/manga/games/music. But what if someone came wanting to learn Japanese trough Shinto texts? Or academic research of their area? If I came here and instead of "For example this indigo la End songs..." I said "For example,
this article here..." (Which is an article that actually came up when I was research the topic for a class), how would your reactions be? Nobody talk like academic papers, nobody talks like shinto texts. Would you say they are "useless" like most do with anime/manga/games/music? Or would you say they have an actual use in their lives, so even if they don't teach natural language they can use it? Would your response be the same if they said they want to use because they got a job/want to travel visiting and staying at temples, and if they said they just want to use it because that's what interest them? Would it be different from anime/manga/games/music? Why?
(Also, fuck English and their singular you = plural you. This was plural you, so not asking you specifically I'm an expert, just throwing some ideas).