One of IJ’s most important topics is the critique of the empty destructive postmodern cynicism that you are referring to. Wallace was in fact trying his best to do more than just reflect. One of IJ’s main and most likeable characters, Mario, is basically a walking sentiment of this. Infinite jest is surprisingly preachy in this regard; “this is water” and some of his other essays are even more so in this regard. that’s why literary critics argue that Infinite Jest doesn’t belong to the postmodern, but rather to the post-postmodern, sometimes also called the metamodern, or the new sincerity. Like a hybrid of modern and postmodern that oscillates between the hip and the banal, between cynicism and hope, fiction and truth.
Here is Wallace on this subject:
“Irony and cynicism were just what the U.S. hypocrisy of the fifties and sixties called for. That’s what made the early postmodernists great artists. The great thing about irony is that it splits things apart, gets up above them so we can see the flaws and hypocrisies and duplicates. The virtuous always triumph? Ward Cleaver is the prototypical fifties father? "Sure." Sarcasm, parody, absurdism and irony are great ways to strip off stuff’s mask and show the unpleasant reality behind it. The problem is that once the rules of art are debunked, and once the unpleasant realities the irony diagnoses are revealed and diagnosed, "then" what do we do? Irony’s useful for debunking illusions, but most of the illusion-debunking in the U.S. has now been done and redone. Once everybody knows that equality of opportunity is bunk and Mike Brady’s bunk and Just Say No is bunk, now what do we do? All we seem to want to do is keep ridiculing the stuff. Postmodern irony and cynicism’s become an end in itself, a measure of hip sophistication and literary savvy. Few artists dare to try to talk about ways of working toward redeeming what’s wrong, because they’ll look sentimental and naive to all the weary ironists. Irony’s gone from liberating to enslaving. There’s some great essay somewhere that has a line about irony being the song of the prisoner who’s come to love his cage.”