Dear Grapevine

For several years now I have been hearing about "Big Book Study Groups," "Big Book Step Studies," and other groups devoted to the Steps as laid out in the Big Book. The trend seems to be that this is the only way to work the Steps. Since Twelve Steps and Twelve Traditions was written by Bill W. to "broaden and deepen the understanding of the Twelve Steps," then why not use it? What's wrong with the "Twelve and Twelve"? Why shouldn't we use AA Conference-approved literature for the purpose it was designed? Or should we get rid of all the other AA publications and only use the Big Book?