Doggone it, Pr. Charlton, you ask profound and sometimes troubling questions here. Cut it out.
But, from within the confines of my own limited perspective on such matters, here are my tentative answers:
1. Is that lack an oversight on the part of the Lutheran tradition, or intentional?
It seems to me it is neither one. Given the methodological priorities, and theological emphases, of the Lutheran tradition, it's difficult to find much room for a robust ethics. It would be a bit like asking if the lack of a premillennial dispensationalism was an oversight on the part of the Lutheran tradition, or intentional. There's just not much there to craft a premillennial dispensationalism, and there's just not much there to craft an ethical doctrine.
2. Is that lack a good thing or a bad thing?
If we Lutherans are convinced that the doctrine of justification is truly "the doctrine on which the Church stands or falls," and if we think that the Lutheran distinctive revolves around preaching Law and Gospel, then I suppose it's a good thing. It's a good thing, that is, in that we are not supposed to confuse justification with sanctification, or Law with Gospel; or be tempted to turn good works into moral imperatives. On the other hand (sorry, Pr. Austin), if we Lutherans are convinced that we are nothing more than a reforming movement within the Church catholic -- that we stand squarely, if a little off-center, inside the Great Tradition of western Christianity -- then I suppose it's a bad thing. It's a bad thing, that is, in that fundamental Lutheran theology amputates several of the appendages of pre-reformation western Christianity as being little more than "accretions," "human traditions," or "abuses" (and this includes most of what would pass for "ethics"). Thus, the Lutheran theological tradition sits awkwardly within the Great Tradition, if it can be situated there at all. What to do? I don't know.
3. Should Lutherans who consider themselves, to be Christian first, western Christians second, and Lutheran Christians third utilize the resources from the greater tradition in answering those questions?
Maybe; but only because being "Lutheran Christians third" would be indistinguishable from not being Lutheran at all. If it is imperative that Lutherans answer those questions (including ethical questions, I presume) from a distinctively Christian perspective, then we don't have much choice but to absorb the resources of pre-reformation Christianity (western or eastern), and somehow graft them onto a Lutheran model, no matter how clumsy the grafting process may be.
Of course, another alternative would be to locate the most sensible and effective ethical system we can find, no matter what its provenance, and adopt it without bothering to pretend that it was incubated within the Lutheran theological tradition. Then we might be able to work backwards and see how Lutheran theology could be accommodated within that ethical system, rather than the other way around.
Those answers ain't much, but they're the best I can do at the moment.
Tom Pearson