It's so weird hearing this. I thought he was the best thing in Ep 1-3, if not the only really good thing. Some lines suffered from the incredibly shitty direction/presentation, but he handled it better than the other actors. Through the trilogy he gave us the primary on-film example of what a Jedi is and how they function in the galaxy. Our only other example is Qui-Gon, but that was more "Jedi in a bind" than typical functions and freedoms. I also think he did clearly grow wiser and more weary as the films progressed.
As far as I am concerned, he earned the right to carry the role if they ever want to bring up Kenobi again, and I would welcome a movie centered around him with good direction for once. The movies were bad, but there was much about them that I wanted to like, and he is the one thing I can remember fondly in the context of those stories and fool myself into remembering the rest as being as good as his parts. I definitely think it would be a bad idea to bring someone else in to play the character. Either let it be Ewan or don't bring him up.