Interesting, I would like to read it.
Happy to share my thoughts.
My interpretation of the term 'otaku' is someone who not only watches anime and reads manga, but is someone who embraces the subculture that revolves around both. For instance, cosplaying at a convention or to buy merchandise such as figurines, amassing a large collection in the process. Essentially, their entire identity is defined by their interest in anime and manga. By extension, their social group will often include other otaku.
In my case, despite growing up with both anime and manga, having seen and read an obscene amount, it has always remained a closet obsession of mine. I'm very much a repressed fan, in that regard. Neither my husband or my circle of friends watch anime or read manga, and some of them aren't even aware that I do (or partially). When I was younger, I kept it a secret frankly because my social group at the time considered it geeky and I was insecure, but now that I'm much older and no longer live in my native Japan, I don't really mind discussing anime or manga to people who appreciate and understand it. However, my current group of friends don't watch or really understand what it is about, so whilst they're aware that I like it, it's not something we ever discuss. My husband has attempted to watch anime, but it's not something he has been able to get into fully, certainly not to the extent that I have. I do have one close friend, who incidentally is Japanese, that loves manga, and we often discuss it when we meet.
Because I was born and raised in Japan, my exposure to anime and manga came extremely early. It's the primary reason why I became a fan. The accessibility of both. That and the subculture surrounding both is, as you'd expect, very pronounced in Japan. If I were born in the UK (or elsewhere in the west), I doubt I would have gotten into anime or manga, potentially at all. I guess there would be a chance that I would, considering how much I enjoy watching and reading both, but equally, I may have latched onto another interest instead.
I am a very big fan of Disney and its films, more so when I was younger. Admittedly, to a lesser extent than anime, but this was only because my exposure to the former was far less.
Having now lived in the UK for over a decade, I see anime and manga as an almost unique way to keep in touch with my home country. Expectedly, I speak English a lot more now, so it's nice to hear Japanese and to latch onto something I enjoyed a lot during my formative years in Japan.
My take on hentai as a genre of anime is that there's a fine line in terms of subject matter, and occasionally it's crossed because it's animation or illustrations, and not something that's been enacted out in real life by actors/models. Whether this justifies the subject matter that's sometimes portrayed is debatable and not something I can comment on as I've seen very few. I suppose, like all sexual fetishes and preferences, hentai has a market, both in Japan and out.
As for hikikomori who also happen to be otaku, both are separate but often connected. I guess, particularly in Japan, anime and manga is often, but not always, seen as a form of escapism, not just for those who are obsessed (otaku), but for everyone. However, there's definitely a correlation between those who obsessively latch onto anime and manga in a big way and those who struggle to cope with the expectations of society (hikikomori). My own thoughts on this are that hikikomori have issues that I don't personally believe are solely down to anime, manga or even gaming, but are part of something much bigger. There are many factors that contribute to their problem.
Like any interest I have, it's been very enjoyable to watch anime and to read manga over the years. It hasn't shaped my day to day life, at all. I would go so far as to say it has improved my life, in much the same way as someone who likes a sport or some other interest.
Hopefully, you've found my answers useful.