You know, a person who chooses to learn a language has every right to choose why they want to learn a language. The fact they want to take the time to learn a language, even if it's just for a single core skill (reading, writing, listening, speaking), makes them that much better of a person to begin with in my eyes. When I was in middle school, learning a second language was one of the most pleasurable experiences of my life. Going into high school, I expanded that further and decided to major in French and Italian language studies when I reached college. I enjoyed it so much, that I ended up taking Latin, German, and ancient Greek for fun. Oddly enough, I ended up learning Italian because of a friend I met in an online game. I spent 5 years of my life learning a language, which included studying abroad my freshman year, all because of a silly game online. I don't even speak to that person anymore or know what happened to them.
As a teacher of Japanese students, I can confidently say that everyone has a reason for learning a language. While most 2D animated fans outside of Japan hope to expand their reading skills, that doesn't mean they are retarded for wanting to do so. A lot of Japanese students only care about speaking English, and the comparison between cultures is what makes me respect language that much more. While it does make me sad thinking they are missing out on so much more by ignoring the other core skills, who is anyone to judge? Learning a language is a very difficult task, and even if some people find it a lot easier than others, it still takes time and effort. To those who want to learn Japanese for a hobby, I respect them for making an effort to begin with.
Teaching ESL and EFL is an entirely different beast. The people who enjoy this hobby aren't required to learn Japanese, yet they do it out of pure excitement and enjoyment. Growing up, we've all had a dream, and even if that dream has changed at some point in our life, something still exists. Why call those who want to learn a language for a hobby they love retarded? I've taught preschoolers who don't even know their native language, and even then I can see the excitement on those children's eyes. I've talked with their mothers and I can tell they aren't doing this for their child's future, but because they want them to enjoy something and be excited. Even if you don't love kids, there really is a joy to seeing someone's face light up when they are having fun.
And it's not just the kids. I've taught English to business students, a Japanese history professor for Korean students, a husband and wife who have some spare time, and lonely widows hoping to meet new partners in their life. I've taught elementary schools, junior high school girls, and high school students who don't even know what they want to do when they get older. It doesn't matter their age, the joy I feel as a teacher knowing they have reached that "ah-ha!" moment in their life and the excitement they feel being able to use the language for the purpose they want is all that matters. A lot of VN and anime fans don't show it, but I promise that at some point they have felt the excitement about being able to finally read or use Japanese in some way or another. Nobody is retarded for that; nobody should feel worse than they already are in a hobby that a lot of people find appalling to begin with.
Language is a wonderful thing, and I feel those who want to learn it for whatever reason they feel like deserve a great amount of encouragement. While I wish individuals would expand their language learning beyond a single core skill, I always need to remind myself that the joy of being a teacher is watching your students grow. It doesn't matter their age, hearing their stories is always a joy. Nobody is retarded for learning a language, and should never, ever feel that way.