Jesus, you're not conservative enough

In all fairness, this sort of thing has been going on for a while. New Testament scholars, for example, are all in agreement that the Gospel writers copied off of each other (most believe that Matthew and Luke used the already-written Mark as one of their main sources), and Matthew and Luke frequently tweaked Mark's text or even left out things that he had included to adjust the emphasis or theological slant of the text.

Later, as Christians began deciding which letters and books they liked the best, a similar process happened in the composition of the Bible. Some very old books (Gospel of Thomas, Shepherd of Hermas, Epistle of Barnabas, Acts of Paul and Thecla, I and II Clement, etc.) didn't make it into the final canon, for historical or theological reasons. Some books, like 2 Peter, 2 John, 3 John, Jude, and Revelation, didn't make it into the final canon in some of the Eastern churches in Persia and India. The Roman church wasn't big on Hebrews, and the churches in Constantinople, Jerusalem, Antioch, and Alexandria didn't like Revelation (both got included in the final canon, probably as a compromise).

Still later, Martin Luther cut out several books (the Apocrypha), allegedly because they weren't originally written in Hebrew (since proven wrong, at least for Sirach, but probably for many of the others too). He also wanted to get rid of the book of James, because its emphasis on works didn't square well with his doctrine of justification by grace through faith alone.

So while this latest attempt is a bit different in that its motivations appear to be more political than religious (although the boundary between politics and religion has been blurred in the US for a long time), it's really simply continuing a very, very old Christian tradition (and a Jewish tradition too, although I'm not as familiar with that process) of editing holy books to fit one's ideological agenda.