I see a lot of people upset about that because of Luke talking through Vader to his father in Return of the Jedi, but, ever the insufferable Rian Johnson defender, I agree with his decision. The reason Rian included Yoda’s force ghost was because we’ve seen Luke’s relationship with Yoda a lot more and a reunion of the two was much more powerful in that moment; arguably, in the films, Luke never REALLY got to meet his father. I bet Luke has interacted with his father’s force ghost post-original-trilogy, but it’s what the audience has seen that’s important. Yoda, the man of great wisdom, was the best choice for a guiding force for Luke in that scene. And including both Yoda and Anakin in the film would have felt forced and too confused.

Now, in my mind Anakin should have appeared to speak to Ben in TROS no question, but that’s another rant.