The worst crime the prequels committed was making the force from a cool zen thing to bacteria in your blood stream.
Sorry, but I am really tired of this complaint. Midi-chlorians did not change anything about the Force itself, they merely explained why some people can access the Force and others can't. The Force still "surrounds us and penetrates us." The midi-chlorians just act as a gateway to accessing the Force.
Well, not to derail the thread
too far, but my objections are simple. One, they are not mentioned in the OT at all, and feel like a way of classifying a Jedi's power without saying "he is the greatest of all Jedi! (trademark pending

).
Secondly, if it is a biological related condition, then Jedi should be in breeding programs to ensure more powerful Jedi are being born, ala the Bene Gesserit in
Dune. The Jedi Order should never be "baby snatching" (as illustrated in the comics) because they should be having kids to continue their order.
Finally, you have, in essence, just created a biology based aristocracy in the Star Wars universe. The only way you can become a Jedi is through proper birthright. It removes any sort of individual ability to learn it and relegates it to being born to the right family. This is rather out of step with the OT, and Star Wars story in general (that off the small versus the big, magic versus technology, etc).
Ok, bigger derail than I meant to, but those are my objections. The midi-clorians may not change the nature of the Force, but they change how people are able to interact with it.
I agree that the SW prequels are the most disappointing because of their
potential to be amazing films. The visuals are fun, the technological know-how is there, the money is there, but the lack of limitations means that the story took second place to the tech.
As for Lin, I am excited for him because, as Nerys mentioned, his background is not just action. F&F may be his most famous work, but it is hardly is only credit. Give the man the opportunity to show his work.