I dunno, I just glanced over at TWoP and read through three pages of comments that were overwhelmingly positive...and everyone seemed to like the lampshading in particular, either because Bobby voiced their own frustrations or because they thought he was justified in what he said.

I don't get that at all. Like you said, it just brings you out of the story. If I'm frustrated by Sam-and-Dean angst, I want the writers to fix the problem not hang a lampshade on it by making Bobby my mouthpiece. And even within the show we've never seen Sam or Dean call upon Bobby unless it was a dire emergency...unless we're supposed to imagine that Sam and Dean are always phoning Bobby up just to vent, which I highly doubt.