I understand moderators have a tough job but sometimes a normal user doesn't understand why their flag was declined or why their post was closed or deleted without sufficient explanation by a moderator. So these disgruntled users often come to meta sites to voice their concerns.
However, some moderators may not be too inclined to explain their actions because they feel cornered and if they write answers defending their decisions there is always a chance of exposing themselves to more criticism from other users.
My question is, do SE guidelines mandate that moderators explain and defend their actions (when asked nicely)? If yes, do they have to write actual answers (which bring closure to the meta posts) and not leave answer-like comments under the post?
And in the event the community doesn't agree with their actions are they obligated to reverse their actions? Or all are mod decisions final?