I see by the discussion my last post sparked that others have given the matter at least as much thought as I had.
Chris Sullivan responds to my hypothesis (which was "that the willingness of lay Catholics to study the writings of the Church has contributed significantly to the popularity of the hermeneutic-of-discontinuity interpretation."):
On the contrary I'd assert the opposite. ... The problem isn't Catholics reading the documents but Catholics not reading them enough and not reading all the documents in question.
But Chris's assertion isn't contrary or opposite to my hypothesis, unless he means the problem he identifies is literally the problem, that it alone explains the discontinuity interpretation entirely. My hypothesis may even be viewed as a special case of his assertion, focusing on one way of misreading the documents.
At An Examined Life, Scott Carson takes the discussion to a point far broader than anything I had in mind:
If one is a devotee of the hermeneutics of discontinuity it is probably because one is already committed to a kind of postmodern rejection of the notion of objective truth. Simili modo those to whom the hermeneutics of reform is attractive will be those folks for whom the Magisterium represents the last vestige of moral and theological realism. Only the former, however, could ever endorse the intellectual egalitarianism that Free Speech Americans have enthroned above the Gospels, and they would think and argue that way whether or not they engaged in more reading and arguing about Church documents.
Scott is writing of those who say, "Vatican II is a discontinuity, and that's a good thing," while I'd written thinking more of those who say, "Vatican II is a discontinuity, and that's a bad thing."
Maybe all the above can be synthesized this way: I suggest some Catholics favor the discontinuity interpretation because the style of argument they use inherently discounts evidence that favors the reform interpretation. Chris suggests some Catholics favor the discontinuity interpretation because they misread the evidence, if they read it at all. Scott suggests some Catholics favor the discontinuity interpretation because they want there to be a discontinuity. Of the three suggestions, I find mine the least probable.