Such a consensus is critical for many reasons, but the most important is unity and harmony in the Church. A big component of that is eliminating the confusion caused by theories of Book of Mormon geography that rely on the premise that Joseph and Oliver were mistaken about the New York Cumorah. This is a serious problem for missionaries, investigators, and members of the Church generally.
Semantic debates about what is a "narrow neck of land" and where such a feature may be located detract from the larger issues of how our acceptance or rejection of what Joseph and Oliver taught about the Book of Mormon affects our ability to encourage others to read and study the Book of Mormon.
Here are more reasons why I think this consensus is important.
1. Joseph Smith and Oliver Cowdery unambiguously declared that Cumorah was in New York (Letter VII).
2. Their testimony was republished many times and accepted by all of their contemporaries.
3. Brigham Young and others confirmed Oliver's teaching about Mormon's depository being located in the Hill Cumorah in New York.
4. Every modern prophet and apostle who has formally written or spoken about Cumorah, including in General Conference, has affirmed what Joseph and Oliver taught.
5. Joseph Fielding Smith warned that the "two-Cumorahs" theory (i.e., the idea that the "real" Cumorah is in Mexico) would cause members to become confused and disturbed in their faith, a warning that has become reality not only for members but for investigators as well.
6. The only reason why LDS scholars and educators reject what Joseph and Oliver taught is because they are convinced the Book of Mormon took place in a limited area of Central America (Mesoamerica). This belief was based on an erroneous assumption in Church history (i.e., that Joseph Smith had something to do with anonymous articles in the 1842 Times and Seasons) and a result-oriented interpretation of the text (i.e., they interpret the text to fit Mesoamerica).
7. Archaeological evidence does not contradict the New York setting; to the contrary, it supports the New York setting, once we accept what Oliver wrote about the numbers of people in the final battles and once we accept what residents in the area reported about finding artifacts, etc.
8. With the New York Cumorah as the starting point, we can understand the text to describe North America, corroborating what Joseph said about the plains of the Nephites, Zelph, the Indians in this country as the remnant of Lehi's people, etc.
9. Even with the New York Cumorah, there remains plenty of room for various models of the geography for people to study and discuss.
10. There is abundant physical evidence in North America that corroborates the text of the Book of Mormon. When more people focus on this, surely more evidence will become apparent.
We all share a goal of encouraging people to read and study the Book of Mormon. Erecting obstacles for prospective readers by creating confusion about where it took place and by raising doubts about the credibility and reliability of Joseph and Oliver is counterproductive.
And that's why we need a consensus about one Cumorah in New York.