The way that I have framed this question indicates that it could be answered by going in a number of different directions. Here are some that come to mind.
One might be to compare Old Testament studies. I think that in many ways Old Testament scholars are ahead of New Testament scholars in applying linguistics to their discipline. Perhaps this is because James Barr was an Old Testament scholar, and he raised important linguistic questions in his seminal The Semantics of Biblical Language. However, studies of verbal aspect in Hebrew go back over a hundred years and continue to generate important constructive studies. Despite this, I still do not see a huge number of discourse studies of the Hebrew Bible—or at least not as many as I would like to see.
Another might be to compare what is being done in discourse studies with what is being done in other areas of linguistically-informed exploration of the New Testament. This is a difficult comparison to make. There seems to be a growing number of linguistically-based studies of various areas of the New Testament. These include, among others, studies of case, syntax, word order, and of course verbal aspect. There are also a number of discourse studies that I have recently noticed. Sometimes these are treatments of individual passages, while at other times there are analyses of entire books. Again, there are some discourse studies, but not nearly as many as there are of other types of New Testament research.
A third way to answer might consider the perception that discourse analysis is something particularly difficult to get a handle on and therefore difficult to use. There is no doubt that anyone who wishes to do serious discourse analysis will have to devote much time and energy to mastering an ever-growing field of study. Discourse studies outside of the Bible are a discipline in their own right, with divergent approaches and methods. One cannot simply use the term discourse analysis and expect everyone to understand exactly what is meant. That is no different, however, from most areas of scholarly investigation. Even within traditional New Testament studies, there are a variety of things meant by the term historical criticism, and the term literary criticism is notoriously elusive. It is a mistake to think that discourse analysis is not definable or usable, however. It can be defined and put to profitable use.
A fourth possible way is to note that there is not the same supportive structure for discourse analysts as there is for other areas of study. Traditional New Testament studies (perhaps one of those difficult words that encompasses too much) is supported by such things as numerous commentary series, monograph series that widely represent their scholarship, and journals that provide a regular fare of similar articles—to say nothing of a lot of scholars trained in such methods who are content to remain so. Discourse studies of the New Testament lacks most of those support structures, and will continue to do so until scholars become increasingly cognizant of what discourse analysis has to offer. Related to this support structure is the recognition—or lack of it—one may receive from doing discourse analysis. Right now, discourse analysts are a pretty small group speaking to each other.
A fifth possible approach is to recognize that there may be some false expectations for discourse analysis, and these hinder its exploration and use. Some of them may relate not only to the difficulty of mastering a field of specialist research, but also simply to the daunting task of learning a new scholarly vocabulary. Another might be a perception of what discourse analysis has to offer in terms of “objective” readings of the text, or of “non-objective” readings of the text, depending upon the side of the question one is on. Some may believe that discourse analysis offers a precise and scientific means of doing a type of literary analysis, but with quantifiable results, whereas others may hold to the notion that discourse analysis reflects the fracture between signifier and signified and thereby loses hold of reality in an age that clings to the last vestiges of certainty.
For whatever reason, discourse analysis has not garnered the recognition that other approaches have. However, that is not to say that it does not have much to offer. I believe that a robust and linguistically well-grounded discourse method—especially one that is grounded in functional language analysis—can potentially offer much for interpreters of the Bible—perhaps more than other, more traditional approaches. It can help the interpreter to focus upon the text as a text, and be able to speak more precisely about the features that make up such a text. It can provide a language to differentiate the various functions that parts of the language play in communication of meaning. It may be able to help to differentiate the ideas of a text from the means by which these ideas are communicated. The focus on units larger than the clause, while also realizing that clauses are made up of smaller units, brings an inherent balance to a discipline such as New Testament studies that runs the risk of being either too focused upon big ideas (often called theology) or too fixated on small units (such as an individual word).
Readers may be interested in knowing about the founding of BAGL—Biblical and Ancient Greek Linguistics—a peer-reviewed international journal dedicated to the linguistic study of ancient Greek. See www.macdiv.ca for details. The journal welcomes discourse analytical submissions as well.