As for Cad Bane. . . okay, I noted in the second season of Mandalorian that all the various callback character appearances still totally worked in the show. You didn't need to have seen Ahsoka or Bo-Katan before to understand who they were, what they were doing, or how they fit into the story.
With Cad Bane, this isn't really the case. He's clearly supposed to be important, but who he is and why he's important is left super vague. . . which is a problem when huge chunks of the finale hinge on his relationship with Boba Fett.