Most of the time when an answer is converted into a comment it is because the answer did not actually answer the question. This most commonly occurs on The Battle Subway but also occurs in PokeBase on occasion. When this happens the answer is usually flagged, but rarely enough to be hidden, and the answer keeps those flags even after it is converted into a comment. However, as a comment, there is nothing wrong with it and no flags are deserved. If the answer was offensive or broke some other rule and deserved to be flagged it would be hidden, not converted to a comment.
And although it is not urgent, it would be convenient so that when a comment is converted, it says "Converted by so-and-so" I stead of "Edited by so-and-so". I am not sure this is possible but I think it would be helpful.