>why i should absolutely learn japanese
You don't have to "absolutely" learn any language, there's no need to exagerate this. However…
It lets you play many videogames in their original language, so not only you dodge the shitty translations, you get the entire meaning and context out of it.
Same thing for Manga.
Same thing for Anime.
It let's you understand their culture and more esoteric concepts like Shintoism a lot better. And I don't mean knowing the customs, I mean knowing the mentality behind them.
It helps you understand a different way of thinking where you respect hierarchies and traditions a lot more as well as having a more pragmatic and stoic look on life. Fortunnally, you'll know more than just Japanese so you can balance that with your own culture and avoid many of their pitfalls.
Because drawing Hiragana and Kanjis is fun and they look cute. Fuck Katakana though, that shit's ugly as fuck but then again, that's what "americanized moon runes" are meant to look like.