I think the reason Of Mice and Mendoes work so well with different casts is that it wasn't written for any of these actors in mind, it is a stage play that Steinbeck wrote, and many actors can fit into it better than one actor trying to fill the shoes of another in a role that may have been written for that first actor.
We learn a great deal when viewing films, and my kids enjoy the black and white ones. We read To Kill a Mockingbird outloud, and during the time we were reading I noticed it was going to be on tv so taped it. After we finished the book we watched the movie, but only after discussing the fact that a whole book compressed into two hours takes a lot of work. We were sorry to see some characters changed, and the story compressed to one year, but overall, it was a very good film. I wouldn't want to see a remake. That film, made in I think 1960, was conspicuously in black and white. That made it more powerful. I don't go looking for old films based on black and white or color, but I do enjoy a b&w.