Ok; I give up. After reading this and other threads which make abundantly clear the many reasons why all camera manufacturers of raw-capable cameras should use a common raw format, could someone please tell me why they don't? Or at least a hypothesis?
I'm pretty sure that the real reason is that the camera companies have fallen into the trap of "oh, lookie here at what we found". None of the camera companies have any real background or experience at file formats or even image processing. The traditional role of a camera company was to provide a light tight film transport and form an image on unexposed film. Neither Nikon nor Canon have EVER been involved in image processing. The only company that does have any track record is Fuji in that they also made film and did processing. Nikon and Canon are really rookies in this field. Nikon and Canon BOTH had a tie with Kodak–Kodak DOES have a long track record of image processing and substantial background in digital processing–too bad Kodak let things slip away. Back before either Nikon nor Canon ever made a digital camera, Kodak sold digital cameras with both Nikon and Canon bodies. The early 35mm camera style digital cameras were wholesaled by Nikon and Canon to Kodak who in turn handled all the sensor work and analog to digital conversion. Neither Nikon nor Canon really liked that arrangement but Nikon broke loose from that triad first and camera out with their own digital camera first...Canon followed by a year or so.
When Nikon and Canon started making digital cameras (and Canon actually started making their own sensors) they decided that now they could control the whole image capture process including the actual file formats. Nikon actually DID already have their own digital file format, NEF (Nikon Electronic File is what I think it stands for) and made the incredibly stupid choice of also giving their raw captures the same extension. Canon started with .crw and for their first full frame (1Ds) switched to .tif (which was also incredibly stupid but followed what Kodak had started as Kodak's raws were also .tif).
From there–and we're only talking 8-9 years ago, both Nikon and Canon have heavily invested and competed with each other on the basis of the "Nikon" or the "Canon" "Look". Which is an absolute joke because neither company has any real experience in doing that. But, you have to understand the typical Japanese mindset...they play the game on the long field and are incredibly reluctant to release anything that hold in their grasp–even if what they hold, the raw file format, really has no secrets or value. Understand, the really big secret when it comes to digital processing ain't in the file format, it's what goes on in the camera where the sensor data is converted to digital data. Once it's written to media, all the secrets are pretty much over and done with. But Nikon and Canon are both very, very stubborn and so far have refused to accept hardly any raw file standards...ironically, both Nikon and Canon's own recent raw file formats have evolved and substantially improved. Why? Because of DNG. See, DNG does point out how raw file data can live with metadata in a safe and useful way. The current NEF and CR2 raw files from recent cameras are so close to being well formed DNG files that it would be trivial to take them the rest of the way to being fully formed DNG.
But, one roadblock to all of this is that the marketplace isn't really pushing Nikon nor Canon to adopt DNG. There are still photographers who think .nef and .cr2 undocumented and proprietary raw file formats are a good thing. Some photographers also seem to have a decidedly anti-Adobe vibe and continue to to think and say that DNG is a bad thing for the industry. That DNG will stifle competition (FALSE), make Nikon or Canon surrender secrets (FALSE), give Adobe ownership of raw processing (FALSE), make Adobe a lot of money (FALSE) or any of a variety of really pretty stupid reasons why DNG is not good for the industry. They are wrong–these photographers that drink the camera companies Kool-Aid, but that's the why the photo biz is...get ten photographers in a room and you end up with ten distinct opinions and the inability to act in their own best collective interest. I've been there, done that and have the tee shirts (and scare) to prove it. I'm a past national president of the Advertising Photographers of America (APA) and I've dealt with other photo organizations such as ASMP, PPA and EP and it's very, very difficult to get any sort of collective effort off the ground and accomplished.
Point of fact, if the photo organizations had any balls, this issue of undocumented and proprietary raw file formats should be an issue that ALL photographers should be able to get behind. Unfortunately, there's enough photogs out there that there is no single unified voice out there telling Nikon and Canon to fix this problem. And I'll tell you that photographers actually arguing on behalf of the camera companies purely pisses me off (which is one reason I tend to be very, uh, blunt about this issue). Personally, I'm of the opinion that any photographer that defends Nikon and Canon's approach to raw file formats is an idiot.