There's no movie in the world as good as a well-written and well-produced radio drama. Movies, as a form of media, are for zombies who either won't or can't think... there's no interaction whatsoever in a movie, the audience just sits there and shuts their brains off.
That's called a popcorn movie, which Star Wars is. It's a movie designed not to require a brain to watch and make lots of money off people who fill those requirements.
(The original three, that is. These last two are quite different but work toward the same ends by milking off the success of the first. If there had been no existing Star Wars trilogy and no established fan base, it's doubtful TPM would ever had been made and certain AotC wouldn't.)
Cine can be an art form, however, though art movies that make it to a general release are few and far between because they're simply not profitable. Most people don't like closely following a story, analyzing it for its messages, and following visual cues and tempi to figure out the structure and ultimately attempt to discern what it was about. People don't have that kind of patience, they'd rather turn their brains off and enjoy the ride of a simpler movie. That's not to say that's bad, movies can be fun to watch. I like the Indiana Jones trilogy, for example, but I'll be the first to say there's no depth there.
To say radio show and a motion picture an incomparable is true, in a sense. They're two starkly different kinds of artform. It's like watching a play made into a movie, it just doesn't work out unless major changes were made in the adaptation (Welles managed with some success, but the point still stands). To say it figuratively, it looses something in the translation. Cine is about the visual, that's why in my opinion the best directors are the ones that learned from the silent film era. To just stick in expository dialogue or narration is too easy a way to get around an obstacle in a film. It conveys the story but not the feeling. Likewise, liberal use of musical cues is a quick way of getting an emotional response from the audience, but they're reacting only to the sound, not to what they're seeing go on in the story. It's true cinema when you take away the dialogue and the music and all the others sounds and the movie still stands on its own using nothing but skillfully crafted and manipulated visuals.
Radio goes entirely in the other way, and it can be no less a work of art, so yes, they are incomparable, but to say one is better than the other is simply false. A fish is not superior to a bird because it can swim and a bird is not superior to a fish because it can fly.
A mediocre piece of entertainment is one that shows you something interesting. A great one is one that prompts you to create something interesting for yourself. (Which of course is hard for movies, easier for radio drama.) A real artist is one who sends the listener/viewer on their own journey, not one who drags the listener/viewer somewhere. The best painting isn't the most realistic one, the best painting is the one that inspires the best internal picture. If you don't realize this, and you prefer your realism junk in which everything is constructed on the screen and you just sit there as a passive audience without needing any brain activity at all, well, all I can say is that you're missing out.
All I can say is you've missed the boat on what a real movie is and have gotten such a bad impression from what Hollywood churns out year after year that you've abandoned the medium and refuse to acknowledge its significance.
A real movie is enlightening, and more than just simply forcing you to imagine a scene in your mind. A movie's intent is to show you, as objectively as possible, a particular element about humanity, allowing you to reflect on it, come to a conclusion about what it means to you, and see yourself by it in a new light. This is not done outright, an announcer doesn't pop on the screen and say "jealousy is filling your life with self-doubt, you must accept others before you can accept yourself" and if one does, well, that's a very poor tactic. The surface story can be mundane and anticlimactic or sweeping and dramatic, it doesn't really matter. Where the true story peeks through the surface plot is where the art comes in. It's not hard to write a surface plot, nor is it really that hard to express your message, what is difficult is to write a story that works and perfectly conveys your message without ever saying it or addressing it in the plot. The movie can be watched without thought and its upper level understood by anyone. Through careful watching and analysis, the message can be found as well. Once you figure out the message and re-watch the movie, you should see that it not only applies to a certain segment or character, but to the whole movie, and everyone in it, and to yourself. That's the brilliance of a skillfully produced and flawlessly played-out film.
To abandon the surface story for the sake of the underlying message leaves a movie that's not enough, it's not strong enough. You can't simply out and out say what you want to say, it won't reach people in the same way it would if you let them discover it in themsleves. A movie should speak to your mind, not your ears. The ideas brought on by a movie will be with you long before you discover the way to put it into words.
Star Wars does none of this. It's a popcorn movie, it's not art. That's not to say it can't be enjoyed for what its worth. Like my example of Indiana Jones above, it can be enjoyed purely on a entertainment level. If you like the Star Wars sort of movie, have at it, but I don't, for reasons I've already said.
Bringing in the opinion of authors to a discussion of radio and cinema, already an apples and oranges situation, is throwing in a banana. I'll skip the rest of what you said because, truly and in short, it's pointless. I'll say it as politely as possible without glossing it over, you have a very narrow view and I don't think you'll let yourself see outside of it.
You missed the underlying theme of 2001, by the way. It's not as simple as that, you haven't broken through the surface. I don't pretend to fully understand it, but I've spent a fair amount of time studying it and come to many points. Read
Also Sprach Zarathustra: Ein Buch für Alle und Keinen, the book/poem Richard Straß wrote the song used as the theme for the movie as well as in a few points during the story to. It will give clarity to many of the more abstract events. Keep track of repeating images and keep a tally of how many times they repeat. Facial expression and subtle actions are also very important. Take note of who is where when something happens and who isn't. Find patterns of events that occur in threes, then try to figure out the significance of the number, the poem will help in this but don't base everything on it. Zarathustra may need further readings depending on how familiar you are with Nietzsche (not just his philosophy, but his writing style and life in general).
What I don't advise is reading others' analysis, interpretations very too widely and you should find your own. I also don't advise trying to link the book to the movie, neither was based on the other and they should be treated as separate works.