I still think Leia is important in that in realise that Leia is his sister, it gives Luke a new motivation and also helps to turn Darth Vader back to the good side in the realisation that he also has a daughter. So her importance is still there in that regard, but I also like how Yoda's last words now carry a dual meaning. One for Yoda himself who is remembering in his final moments, his journey coming to this point and to also give Luke a clue that he is not alone in his journey to help his father back to the light side of the Force.
In any case, TWC has turned out to be the best thing to come out of the prequel trilogy. While I may not be a fan of the prequel trilogy of movies as much as I am the original trilogy, I have come to respect where TCW has taken us. It may have started out rusty but it managed to turn itself into a really good direction and gave us a lot of really great stories over the course of its life. It is hands down better than the entire prequel trilogy IMO.