It's shallow intellectually, but it doesn't even have any depth emotionally. At least with most other popular TV shows there's depth in terms of personal relationships. There's drama that's more emotionally interesting. Black Mirror seems to be optimized for people who are blunted both in terms of intellect and social emotion. It's one of the most boring TV series on Netflix, which is a shame because there's not much else that even attempts to be interesting in a more sci-fi way.
I think the only reason why people find value in Black Mirror must be because of references. Like how they love jokes on Reddit when they refer to something they all know. People must be like, "Ahaha, they're referencing how people are always on their phones. So true. LOL look, it's trollface!! Dude, look, trollface is on TV. I know trollface. Haha this show is great." What else would people be getting out of it?