I can see where you're coming from, for sure. I just find it restrictive to demand all art have conventional characterization. There's tons of examples where there could be said to be NO characterization in a narrative, though I think that's using the wrong language, to say something has no characterization because it lacks dialogue, or scenes that follow a three act structure. Like The Color of Pomegranites, a film I didn't even like, where it's pretty much a museum expo on film with a very, very loose narrative progression, mostly showing a character as he ages. I don't think that's automatically in error, regardless of what medium it's in. Different ideas command different methods of how human beings should be presented to the audience. Perhaps you're onto something with it being out of whack with the idea of serialization, but there are plenty of literary works that were serialized and 'devoid' of traditional characterization, maybe the most extreme example beig Finnegans Wake. I don't have TV examples though, but there's nothing that inherently seems flagrantly defying the possibilities of the medium to operate outside the bounds of clarity.
With the case of Nadine, come to speak of it, I feel that the lack of clarity is intentional. A lot of the Return feels 'in media res.' We see characters and we begin to wonder if the old situations they're in still are going on or not. When I saw the scenes between Norma and the guy trying to get her to sell her diner, I had no idea what the relation was. Was he a boyfriend? Were her and Ed married? It made me pay close attention to see if the context would ever drop. A very good example that I thought worked well was the moment it's revealed that Shelly isn't with Bobby anymore. When they're having the family meeting, and Red pops in, and Shelly goes and kisses him. I had NO idea what was happening. I thought Red had hypnotized her, or that she was being weirdly open cheating on Bobby... but as it went on, the 'feel' of the truth set in. But until I decided, well, they must have gotten a separation, I felt very 'together' with Bobby and Becky, who seemed equally caught off guard... I thought it was an effective use of witholding information, and presenting information without directly and clearly offering it to the audience. And, despite the lack of explanation, did actually, at least for me, further my empathizing with characters.
I don't mean to be disagreeable for the sake of it though, you're totally entitled to your reading. I find disagreements about 'characterization' and how it should function an endlessly debatable topic.
Recipe not my own. In a coffee cup. 3 TBS flour, 2 TBS sugar, 1.5 TBS cocoa powder, .25 TSP baking powder, pinch of salt. 3 TBS milk, 1.5 TBS vegetable oil, 1 TBS peanut butter. Add and mix each set. Microwave 1 minute 10 seconds. The cup will be hot.