I don't think that's quite true. If you read stories in the New Yorker, or the Atlantic, or similar publications, then you'd find equally "naval-gazing" writing from "real" reporters.
When I write a post, or when a journalist writes a story, or when you write a comment, you want to have an angle: something that sets your writing apart from the other thirty people who are writing about the same thing. Many publications today will cover detailed information about Mountain Lion. Gruber knows that. Further, there's not actually much new in Mountain Lion: Gruber successfully summarizes the new release in a handful of words in a middle paragraph. While I suppose he could go into more detail on interface minutia between Contacts and Address Book, or pontificate on why Notification Center on OS X looks more like Growl and less like the iOS pull-down, even doing that would provide him relatively little material.
Instead, Gruber focused on the culture of the event. From a company so well known for massive product releases and on-stage demos, the idea of doing not just one, but a large number of in-person demos across the country represents a substantial shift. It could symbolize any number of things, from a lack of confidence to a desire to repair image damage from Foxconn, which is why Gruber finds a need to emphasize how polished the presentation was and how the event was set-up in detail.
I can understand why this might feel like naval gazing, but to me, it's anything but. Gruber is in a unique position to comment on the cultural shifts of Apple, precisely because he's so involved with that selfsame culture. If he's going to comment on Mountain Lion's release this morning, that's going to be his angle. It's completely fine if you don't find it interesting, but questioning his competency, or calling this approach conceited, is wrong.