It’s true that being briefed by anonymous “senior” officials is largely an exercise in getting spun, but in its defense doing on the record interviews with senior officials is also largely an exercise in getting spun. And I do think anonymity has some value in that by preventing journalists from doing sensationalist stories based around a single direct quote it forces you to focus on the big picture of what the officials in question are trying to say.
For example, if you looked through a transcript of yesterday’s conversation with bloggers with an unscrupulous eye, you could probably find a Tim Geithner quote about California or Greece or something that, sexed-up with a juicy headline, would constitute “news.” But since we’re not allowed to quote directly, only characterize in general terms what was said, and I can convey to you that Geithner talked a bit about both California and Greece and was sensible but didn’t have any earth-shattering insights into the situation.
Personally, though, I’ve never found speaking to important political figures either on or off the record to be incredibly valuable in terms of actual information. People are generally more willing to make jokes when it’s off the record, so it’s more entertaining to participate in those kind of briefings. On the other hand, it’s much easier to build an item around a direct quote so it’s more professionally valuable to be on the record. But it seems to me that the people who do the real value-adding reporting are mostly talking to lower-level people—nobody ever gets the real scoop from anyone remotely senior.