I feel that cutting the part of Tom Bombadil in the upcoming movie is ridiculous. He fills a pivotal role in the plot of the story. True it is not as considerable as Frodo's, Gandalf's, Sam's or even Elrond's but none-the-less.

Up until the point of the hobbit's meeting with him I don't think that any of them truly grasped the power of the ring or the necessity for its destruction. Not even Gandalf in his conversation with Frodo in the study at Bag End convinced Frodo of the magnitude of the situation. Tom is also a key figure in relating the Elder Days of Middle Earth.

Taking Tom's character would cause potentially cause detrimental damage to one of the key element's in the story: The power of the One Ring. Remember that the whole concept of the Ring is esoteric to any hobbit even Frodo, Bilbo and even Smeagol (Gollum). Gandalf simply introduced the concept, he could not relate all that was necessary to Frodo, that was Tom's job.