people meme about how it's just the same thing over and over, but that episodic nature made it easy to just jump in and watch random episodes of it when it was airing on tv. each character has an extremely clear personality that you understand within a few seconds of watching them, which makes it even simpler to understand. it being on adult swim made it accessible to more people. it had a lot of erotic designs and the dynamic of "overpowered demon MC + school girl who has control over him" is fun, plus the isekai element was still fresh at the time and didn't devolve into narou-kei dogshit: kagome served purely as our window into the world of the show, rather than as an overpowered hero that everyone has to jerk off.
also as
>>280201453 said it did pretty good showing a lot of japanese culture, and it didn't have a 4kids type dub that tried to hide it so there was that too.