No Books but THE Book?

I've long been curious about why some Christians are more suspicious of extrabiblical literature than they are of extrabiblical oral communication. It's as though there's something about committing Bible teaching to the printed page that makes it more deserving of scrutiny. A comment I read recently resurrected my curiosity about this matter.

For a number of reasons, one of which is to insure consistency in what is taught, our church uses prepared curricula (either Bible study guides or complete books) for most of our adult education classes. At the end of each quarter we ask participants to fill out evaluation forms that ask how, if at all, the class has assisted their spiritual maturity. For those classes in which a workbook or text was used, one question asks how well it helped the student to understand and apply the subject. In response to this question an anonymous party replied "Better steer clear of books and study with the Book and let the Spirit do the speaking." This same sentiment lies behind aversion to the use of biblical commentaries. However, I have yet to meet anyone who consistently applies the mistrust of written materials to other forms of Christian teaching about the content of the Bible.

I've asked other Christians who've voiced this view whether they attend a church. When they replied affirmatively I asked whether their pastor uses the sermon time to simply read extended portions of Scripture without making any explanatory comments about a text's meaning and application or using illustrative material that doesn't come directly from the Bible. Of course, the answer is no, yet this doesn't seem to bother those suspicious of books. But it should if, in fact, the only words the Spirit uses to teach are those of Scripture. What is it that makes oral explanation of the Bible's message acceptable and written teaching suspect? Would a transcript of a biblically faithful message suddenly become unspiritual simply because it is now in print? A related question is how are we to understand the nature and purpose of the spiritual gift of teaching if we are restricted to using only the words of Scripture? 

I understand and share the concern that we recognize the Bible as our ultimate authority but the use of books, like sermons, does not necessarily undermine that conviction. No books but the Book? No. All books judged by the Book? Most definitely.