"Since art is a communication skill and if your image isn't communicating what you wanted to say to the audience then the comments should provide feedback on how to improve it so the audience can get the message you wanted to convey better." That's a good approach for any critic, but I don't think having the artist write an essay first on what they where trying to achieve is very practical. That's why I tend to comment on images that "speak to me" anyway. There's a certain chance in those cases that the communication might be actually working. Of course, technical or beginner's questions are a different story. These are fairly easy to express and most of the time as easy to answer.

-- I'm not mad at you, just Westphalian.