I didn't know what you meant so I googled it. The technology is cool, but the content is ... problematic.
From urban dictionary:
"Waifu" is used to refer to a fictional girl or woman (usually in Anime, Manga, or video-games) that you have sexual attraction to, and you would even marry.
A big part of it you're missing is that it's a joke. Anime fans definitely know they're weird, and are very passionate about the things they like (and are conscious of that), and thus a lot of humor in the community is self-deprecating and ironic (for example, calling your favorite fictional character your "waifu" or "husbando"). The fact that outside observers might think it's "problematic" is kind of the whole point.
