McCluhan has thoroughly considered the effects of the medium itself in his essay.  I found his point of view interesting though I'm not sure I fully understand it, because while many of his points of view are compelling some seems contradictory.  In essence, I think he is saying there is a fundamental way in which we absorb media determined by the medium used in and of itself.  This idea has been reestablished as new media and technology have developed.  For example, McCluhan references Cubism, which fundamentally changed how people take-in visual art works.  It told the audience to see the work in a particular way.  "The effects of technology do not occur at the level of opinions or concepts, but alter sense ratios or patterns of perception steadily and without any resistance."  I really enjoyed this statement, and think it applies to cubism appropriately.  However, the impact of cubism is really the function of the style and not really the medium itself I'd say; it's still a painting.  But it is because it's a painting that the audience has to change their approach in viewing.  I think this is really the way in which "the medium is the message"; there is something about a work's particular medium that affects the audience in a way no other medium could. 

Really, I'm torn by this argument.  In one way I totally agree that an art work maintains an element of its power in the exact medium it showcases.  But to Mcluhan's stance overall, I see a problem in saying that the medium is more important than the message, and that's what he seems to be suggesting.  I like the claim that people "never used to ask what a melody is about", and I agree.  But a piece of much is much more about the melody, and different songs can convey very different emotions.  To respond more directly to the author: A melody can work very effectively, but it is not obsolete because it uses similar theory as older songs.  Perhaps I'm getting confused by his statements, specifically that "if it work's it's obsolete."  This one stuck out to me, mostly because Mcluhan seems to believe it so strongly yet it sounds like a contradiction. 
And while I do believe in experimentation in art and "art from adversity", there is nothing lacking on a fundamental level of an art piece if it is not actively redefining its medium.  Sometimes- often, actually- the medium is nothing more than a vehicle or tool to deliver a more important message.  Unless I've missed something critical (possible), this is Mcluhan's argument.