I've addressed this before on this blog but there's a key point to emphasize.
For some people, geography doesn't matter because they have a spiritual witness that supersedes any "physical" witness. That's axiomatic: if one is active in the Church, presumably it's because one has a spiritual witness. However, not every member of the Church is active; people have different spiritual gifts (D&C 47). Some need a physical touchstone, a tangible evidence of some sort, or some form of corroboration of the reality of the Book of Mormon text. They think, "How can I trust the spiritual messages of the book if I can't trust the physical messages?"
The two big problems with the Mesoamerican model for Book of Mormon geography are 1) there is zero evidence of the Book of Mormon narrative there and 2) the proponents insist Joseph didn't know much about the Book of Mormon. Regarding point 1), I have read all of Sorenson's works and most of what FARMS and the Maxwell Institute have published, and the best they can do is find analogies or plausible similarities. They have to adjust the Book of Mormon text to make it fit, such as changing the meaning of "north," changing the meaning of "horse," "sheep," and other plants and animals, etc. But even then, they explain that there is no evidence of Book of Mormon culture or people in Mesoamerica because Lehi's group was so small it essentially vanished. It's difficult to separate the Mesoamerican theory from the assertion that the Book of Mormon is fiction; i.e., insisting the Book of Mormon events took place in an area and culture that have nothing to do with the Book of Mormon narrative is equivalent to saying the Book of Mormon is purely an allegory or parable. Regarding point 2), to justify the Mesoamerican theory, proponents insist Joseph Smith did not understand the Book of Mormon (but the Mesoamerican proponents do) and merely speculated about its setting, that he didn't learn about the Nephite culture from Moroni, etc.
Both of these problems are serious issues for those who study the Book of Mormon. Undermining the credibility of the translation regarding directions and animals also undermines the credibility of every other aspect of the book, and undermining the credibility of Joseph's own statements about his revelations and familiarity with Book of Mormon people undermines the credibility of everything else Joseph said and wrote. The Mesoamerican theory is a major deterrent to honest investigators and a major factor in people losing faith in the Book of Mormon. This reality is reflected daily on the Internet for anyone to see (not to mention in every group I address).
Here's an excerpt from my book Moroni's America, to be released on July 1st for the 4th of July weekend: