Bible translations is that from time to time it is necessary to update them. The reasons include that as time goes on we understand more and more about Hebrew, Aramaic, and Greek. Also English, or whatever language you are reading changes. Dr. Mariottini has posted an inciteful article about the completed Revised NIV. I agree with him that we don't need to "help God out" by purposely inserting words for which we have not textual proof for inserting. When you compare translation to the original texts, I'm always amazed that some times they are right on in agreement and sometimes they are not. At times the KJV actually is better than the NIV and at other times, it is not. It's going to be interesting looking at the new NIV and seeing what is different.
Dr. Claude Mariottini - Professor of Old Testament: The Revised NIV: A Step Backward