Anime has grown increasingly mainstream over the years, thanks in most part to the growth of the internet and how it provided a larger fan base. What was once strictly the purview of die-hard fans swapping low quality fan subbed VHS tapes with one another is now a hobby open to anyone thanks to streaming sites offering legal alternatives to watch your favorite show, sometimes mere hours after it had concluded broadcast in Japan. That's quite a difference from how it once was where the market was at the mercy of a license to slowly bring a complete show out over the course of some months, sometimes years.
It's entirely unsurprising that today's generation would be fascinated with the medium. It offers a plethora of genres with a wide range of appeal. The varied subject matter helps distinguish itself from most Western animation, in particular anime that handle more mature themes. Adult animation is nearly all comedy with very few exceptions to the rule. Those looking for a more mature story that's animated can readily find that in anime.
Another reason today's generation might enjoy anime is a rather obvious one: they might simply enjoy the animation. Action animation coupled with more mature themes can create an engaging product are not easily found in Western animation anymore. Korra and Avatar exists but they've both long since been the exception rather than the rule in this matter.
Beyond that, there's also the culture surrounding the medium. Conventions, online communities, local clubs, or even just watching with some friends give the hobby more of a communal aspect than it ever had previously.
There's more reasons beyond those listed above and many combinations of such will lead to why an individual enjoys the medium as they do. It's easy to see that while anime may not be as profitable as ever, it's certainly more popular than ever as it slowly re-enters the mainstream with this new generation of fan.