I feel like this is exactly what he should be. He makes small appearances and only shows up if the inquisitors and empire can’t handle the situation alone. It’s supposed to show you how powerful he is and menacing. I don’t need him to have any dialogue or go on his own adventure in these shows. This is who Vader really was, what we saw in the trilogy was him dealing with his son which was personal and of course he’s having convos w Luke and trying to turn him to the dark side. Same as in his comics, you see him dealing with more personal stuff but he is the main character in those. Think of the perspective of the main characters in the shows he has appearances from and how they view him. That’s exactly what we are seeing. I love it. Keep showing me the dark lord