I can see both sides of this. Of course unmerged match is a status which should be used to mean, "There are significant differences that need to be resolved before this merge can go forward," or "It is not certain these two profiles represent the same person." On the other hand, we have some Wikitreers, especially those who have joined more recently, changing pending merges to unmerged match because of some very trivial difference between the two. These unmerged matches are undoubtedly well intended, but are sometimes done by people who don't realize it is causing unnecessary problems and delays.
Generally, where the two profiles clearly represent the same person, differences can be noted in the bio section of the merged profile, and data fields in question can be marked as uncertain when called for.