Thoughts on the subject from three different sources, and from varying perspectives:
"Those who embrace the descriptive hermeneutic argue that the church today should observe these descriptive passages for at least three reasons."
1. "Since they are found in Scripture, they must be biblical."
2. "...the Bible is our sole guide in matters of both faith and practice." If we can trust Scripture for what we believe (orthodoxy), we can trust Scripture for what we practice (orthopraxy).
3. "...the early church set a historical precedent for all future congregations. Thus, all we need to know about church ministry is found in the Bible." -- From Doing Church: a Biblical Guide for Leading Ministries through Change, Aubrey Malphurs, Kregel Publications (much of this book can be viewed a Google Books), pp. 73-74
On the Baptist Board a few years back, Scott Ransom summarized some class notes he took in a moral theology class. According to him (and the teacher) a few guiding hermeneutical principles for determining the scope of biblical commands were:
a. it is addressed to an enduring audience
b. it is based on a permanent relationship
c. it is repeated, especially transculturally
d. it is supported by prescriptive, and not merely descriptive, passages
e. it is supported without abusing its literary genre
f. it is taught as principle, not merely a manifestation of a principle.
"There are two main points that they made that I found compelling. One is that if you make New Testament patterns descriptive, and therefore non-authoritative, we lose any basis for ecclesiology as a whole. This is because there are very few "positive commands" to us with regard to church practice. Almost all of our theology of church is based upon descriptive passages rather than positive commands. Ecclesiological issues are issues that deal with things like how often we meet, when we meet, what we do when we meet, who may meet, how often we partake of the Lord's Table, who may partake, who the leaders are, that we should even have leaders. They have as their basis New Testament patterns rather than New Testament commands. If we make New Testament patterns optional and descriptive, rather than binding, we are left to pick and choose which patterns we want to hold and which ones we would rather ignore. Is this acceptable? It is if New Testament patterns are descriptive. It is not if they are meant to be prescriptive.
"Paul told Titus to appoint elders in Crete. He told Timothy what elders should be like. He lays down ground rules for how elders should function. But he never actually states in positive command form that all churches must have elders. [or that all elders must meet these standards.]
"even more compelling argument for New Testament patterns being prescriptive rather than descriptive is Paul's use of the word 'traditions.' In the NIV most of the instances where Paul uses this word has been translated 'teachings' but in fact the actual word is traditions (paradosis). II Thessalonians 2:15, is a perfect example of such an instance. In this passage Paul exhorts the Thessalonians to hold to his traditions whether by word of mouth, or letter. In I Corinthians 11:2 Paul praises the Corinthians for holding to his traditions just as he passed them on to them. Later in the passage he rebukes them for altering the directives he passed on to them for how they participated in the Lord's Table. That they had altered these directions in their practice was condemned.
"It seems that Paul not only imprinted the churches he planted with doctrine, but also with a model or example of practice to follow. Paul refers to himself, how he lived, and what he did as a model for churches to follow. Paul praised the church in Thessalonica for imitating the churches in Judea (I Thes. 2:14). The Thessalonians were so faithful in upholding this model that they themselves became a model to other churches (I Thes. 1:7). To the church in Philippi Paul exhorts them to put into practice everything they have learned, received, heard, or seen in him. In other words, if Paul set up the church to meet and operate in a certain way, the churches should not feel they had any right to modify this practice. Instead they strived to uphold the patterns they received, and they were commended for success and rebuked for failure." -- Maintaining passionate conviction without causing division by Eric Holter, from paragraph "Toward a House Church Theology"