Why are times so tough for business magazines?

As a longtime inhabitant of businessmagazineland, I stumbled over a few of the assertions in David Carr's column on the death of the business magazine in today's NYT. For example:

Business magazines used to relish explaining all the complex new financial instruments that Wall Street was using to pile up profits. But now it has become clear that the titans who were wielding those obscure tools had no idea what they were doing — even less an idea than the journalists in some cases.

Uh, no, business magazines seldom wrote about that kind of stuff. It was too ... complex and Wall Streety. I'm also dubious of Carr's argument that the biz mags are being especially hurt by the real-time nature of modern news—business news (at least, investing-relevant business news) has been delivered in real time for decades. And while his point that business journalism is less relevant in an age where Washington calls most of the shots at least seems sensible, it does ignore that business journalism really came of age in the 1930s—another Washington-centric decade—with the birth of Fortune.

So what's left? Why has the business magazine business turned so horrible? Two of Carr's explanations make sense:

1) Business magazines are aspirational, and not so many of us are aspiring to be CEOs these days.

2) All advertising is down, but the particular ad categories that kept business magazines going—financial, consulting, cars, etc.—have been especially hard hit. Not a lot of Spam ads in Forbes.

I doubt that's all there is to it, though. Obviously, lots of people are reading stuff online instead of on paper, but that doesn't explain why business magazines in particular have been so hard hit. Maybe it's something to do with us all having less patience for long narratives in this age of constant distraction—WiFi in airplanes seems especially dangerous for the business magazines, since I always got the sense that most reading of long  Fortune articles was done on plane flights (for TIME and People, obviously, the big threat would be WiFi in dentists' offices). There's also the vicious circle of less advertising leading to less editorial content which gives people less of a reason to buy the magazine which leads to even less advertising, etc.

Any other suggestions?

Update: Chris Roush channels Nat Ives quoting Audrey Siegel, exec VP/director of client services at TargetCast:

‘Over the years they went to a model that doesn't ask the reader to pay their fair share,' said Ms. Siegel. ‘They were really reliant on advertisers. And when the bottom fell out — when certain categories such as technology, finance and luxury goods really pulled back — the magazines were left holding the bag.'

That sounds about right. Although it should be said that the rewards of moving to that ad-dependent model were pretty spectacular for a while (in the late 1990s especially). Which has made changing it all the harder.