As I go at length in this answer, I believe the recent kerfuffle over the comment system stems from a misunderstanding of the comment system's purpose. I would like to request that the FAQ be amended to include an answer to a question somewhat like "What kind of comments should I leave?" and "What kind of comments should I not leave?"
The current (implicit) policy (consisting of merely guidelines that the community may interpret, rather than hard rules) behind the comment system I believe is that comments are primarily intended to provide clarifications to questions and answers by identifying errors and ambiguities, and that any contributions of substance should, be either edited into the original question/answer whenever possible or fleshed out in a wholly separate answer, with exceptions made for short (essentially chat-like) contributions of length less than a paragraph of 600 characters.
Corrections to any misreading (if any) of the FAQ and suggestions for how the policy should be worded are welcome.