As "truth" in the realms of philosophy, critical theory, and literary studies is almost purely subjective, I find it irrelevant to the discussion. Interestingness is unquestionably a motivating factor in selecting who and what is taught, but it's not neccessarily the students whose interest is factored in when making that selection. Interestingness over time, to multiple groups and/or generations, seems more accurate a scale. In addition, it isn't too hard to defend thinkers like Nietzsche, Derrida, Zizek, Marx, Hegel, Lacan, Freud and the like on grounds well beyond those considered "interesting." Are Marx and Engels taught because they are interesting, or because their works are challenging and brilliant? Frankly, most of the people listed are so fucking boring to read and understand that after 4 years of undergrad work, I was ready to build a time machine so I could go back and edit in some illustrations just to break the castle-walls-of-text monotony. Zizek is cool, lot of movie references. Foucault is probably the most "interesting" of the possible selections, and he is really only featured in one or two departments on a whole campus, while Hegel and Nietzsche (much less interesting to read in my opinion) are all over campus, they even show up in some business and advertising classes.

Well, that was a rant to nowhere. What do the kids do in this situation? TL;DR - I disagree with the article that student interest dictates the canon on any given university campus, but concede that interestingness is a factor in canonization over time.