That's the entire point? It's meant to be a group of rejects that nobody cares about. That's why she uses them. And yeah, if we never saw Bucky, Alexei or Yelena in the MCU again it would absolutely suck. Bob was an interesting character who I'd love to see again. In fact the only one I'm not really fussed about was Ghost. Even Walker is interesting enough that I'd see him again.
I think you are confusing the premise of the film within the MCU and the fact that most people don't care about these characters that much in the real world. This is borderline the same as the suicide squad. No matter what the premise of the characters in the film, people watching have to care about them.
You clearly do so perhaps its just me. I was just expecting more based on the positive reviewing of it. As I said, it was fine. I was expecting better than fine.
