The Insider Program is certainly genuinely useful, for both MS and consumers. I'd argue that this whole debate over navigational concepts being held now, rather than surprising everyone on launch day, is already proof of that.
Still, it's when consumer interests with a large number of votes on uservoice can't be realized, for whatever reasons, that the Insider Program is in danger of at least looking like a PR stunt.
During the prologue of most of Terry Myerson's recent speeches, he's often given me the impression that all popular uservoice requests do/will have their impact on the feature set.
On the other hand, the few articles on WCentral hinting at MS' position on navigation suggest that MS has long ago drawn a line in the sand.
To me that seems like mixed/contradictory messages. That's were I locate the "PR stunt" component of the Insider Program (when coupled with uservoice).