Why target anime in particular instead of (for example) all TV and movies? Is it more about having a beachhead, or is it that there are important characteristics that make anime unique compared to other media?
1) Strong user/viewer affinity for the category. Generally speaking, you don't find that your typical Grey's Anatomy viewer is a "medical drama fan," who seeks out other medical dramas at every opportunity. Likewise, a rabid Family Guy viewer is probably not an "animated comedy fan," barring a very tiny and borderline-insignificant segment who is. They might be fair-weather fans, but their consumption of those categories is ad-hoc and show-dependent. Anime fans may come to the category seeking a particular show -- Cowboy Bebop, Attack on Titan, or what have you -- but many of them stick around for anime as a category. Someone who likes Law & Order isn't going to seek out other legal procedurals, but someone who likes a mecha show is going to look for more mecha shows.
2) Anime is underrepresented on TV/movie services like Netflix, or in other "mainstream" TV/movie sites and aggregators. (That said, there are anime-specialist players in these markets, such as Crunchyroll and Anime Network.)
3) High fan engagement online, more so than with many other categories of film or TV. Thus, a more addressable user base.
Of course, these factors can also work against you. As another commenter has pointed out, the characteristics that make anime unlike other genres also makes bridging the gap between anime and other genres very challenging. Anime companies are usually in the business of addressing the TAM in the anime category; they seldom find success using anime as a beachhead to attack TV or movies in general. Not saying it can't happen, or that it's never happened. But it's difficult.