Quoting the comment guidelines:

The test for substance is a lot like it is for links. Does your comment teach us anything? There are two ways to do that: by pointing out some consideration that hadn't previously been mentioned, and by giving more information about the topic, perhaps from personal experience. Whereas comments like "LOL!" or worse still, "That's retarded!" teach us nothing.

I do believe simply offering a different perspective falls under the guidelines of a good comment, without the need for elaborating prematurely. That would be like pre-mature optimization; I might guess incorrectly what to elaborate on. Feedback gives me greater direction in what to answer.