Any kind of stats to back that assertion up? Personally, I think our lack of great offensive teams in some of the past few years has to do with our player's limitations on O, as opposed to what D we play. In the years in question, we haven't had the balance needed for really good offensive teams, and that's due to the specific mix of players we've had.
Also, the year you're talking about, '09-'10, when we began playing zone exclusively, was one of our best offensive teams ever. '11-'12 was pretty damn good too, so although I'd agree that the past few years have been a little hard to watch on the offensive end, that's A) a pretty micro-trend in the scheme of things, and B) not really related to our D much at all. If you look at the '09-'10 team specifically, one of the strengths of our offense, transition, was at least partially due to the D we played, and how that flowed into the transition game.
Blaming it on JB spiting the media is kind of a bizarre twist too. Do you really believe any coach makes major, team- and legacy-defining decisions simply to spite the media? I mean, we all know he's got a petty/vindictive side, but c'mon, you're telling me the reason he plays zone exclusively is not because he thinks it's an effective strategy (the reasons for which he describes in detail in his book), but in fact that he really just wants to punk the media?