There has been a great deal of exactly that feedback from attendees (including me) and Chris Anderson is definitely hearing it -- he addressed it at length from the stage twice this year. However, he seems to think that is a necessary side effect of producing talks that will be viewed millions of times (I think he said ted.com has hit a billion views now). I'm not sure I agree, but in any case I enjoyed it more back in the day when you never knew if the next talk would be an epiphany or a train wreck!
Today TED is all polish and perfectionism and production value. The Academy Awards stage design and videography is planned months in advance. Speakers are carefully vetted, recalibrated, tweaked, and tuned among an upper tier committee. Corporate sponsors are courted by a large international sales team, and these accounts pay enormous sums for the chance to create branded "experiences" for the ticket holders. Speakers (those whose egos allow it) are coached relentlessly about storytelling, sincerity, posture...
These efforts may have increased the average-overall quality of the talks, and made the talks more palatable to a wide audience. But that came at an expense of a certain kind of magic.