As it turns out, the sponsors.
As my friend (and critic) Phil Windley opined in his blog, whereas much of the content was exceptional (Lessig, Clayton Christensen, etc.), a significant amount felt like it had been bought and sold. And it had. Sponsors demanded (and got) speaking slots based on their willingness to pay. While we tried to hold to editorial values, once the money was in our bank, it changed everything.
For the worse.