The reason that Nikon CHOSE to underexpose the images is a well-thought-out reason. With digital cameras there is a limited range of exposure. Probably about 4 stops or so. If you blow away the highlights by overexposing even slightly, you can never recover any of those details, since the pixels have gone to pure white. But, if it is slightly underexposed, there is still detail in the highlights, and in Photoshop you can use the Levels or Brightening functions to pull all the detail you need from the shadows. I have experimented with this quite a bit.
The real situation is this. If you are going to use digital cameras, you had better learn how to use Photoshop, or any good image editing software. The camera's exposure range is simply too narrow to capture even as much as a good transparency film can capture. You have limitations, and you must work around them by shooting low-contrast scenes as often as possible. If you shoot for the shadows, you WILL lose the highlights. You are shooting for the shadows when you use the exposure compensations for flash or regular.
I admit that Nikon may have gone a bit overboard with the underexposure, but I suppose they chose to be conservative. You will have to adjust to the narrow exposure range, or go back to film. Within a few years, they may have a CCD or CMOS chip that can record a better range of light, but for now, we have limitations. I too use a bit of compensation. I find that +0.3 for regular exposures in low-contrast situations is quite satisfactory. But if you get into a high contrast situation, and do ANY + exposure compensation, you WILL lose your highlights. Now that you have read this, experiment a little and see if you don't find the same thing I have with my D100.
In the old days, when cars were first introduced and you bought one, you had to learn to be a mechanic to use it. Technology had not progressed far in cars, so the user was greatly responsible for overcoming the inherent problems. Today, we have a new technology, digital imaging. It is not yet ripe, so we early adopters must learn to overcome the inherent problems in new technology, just like in the old days. Buy Photoshop, learn how to use it. It IS necessary! And, it IS worth it!
Below are some sample images that test my assertions:
Image 1: This was shot using 3D-Matrix Balanced Fill Flash with shutter on Slow Sync and +0.3 EV flash compensation. Please note the very pleasing look of the subjects and the background. But, also note the little boys hand on the far left (on shoulder). With +0.3 EV overexposure the details in the hand are beginning to blow out. If I had used +0.7 EV overexposure, I would have lost the detail in the hand completely, and most likely in the hair highlights too. As it is, the +0.3 overexposure worked fine. A normal expsosure would have done about as well.
Image # 2: This was shot with 3D-Matrix Balanced Direct Flash with normal front-curtain shutter setting, and +0.3 EV flash exposure compensation. I cannot see any burned out highlights at all, since this was a very low-contrast scene, with no backlighting. I note that my daugther's white skirt is beginning to look a little bit washed out, since the 4-stop range of digital is pushed to the edges.
So, in summation, it is the CONTRAST of the scene that determines whether you will lose detail in the highlights, and need to under or overexpose your images. This is different from film, with its better range of light capturing abilities. If you shoot with an eye toward contrast, you will make better images with both film and digital.
I wrote the N80 review here on the Nikonians.org website. (https://www.nikonians.org/html/resources/nikon_articles/body/f80/f80_1.html) I am now working on a D100 review in tremendous detail. This review will be a completely "hands on" review with an emphasis on a users perspective, not a scientist with a 40 power microscope and lens test charts. I need your help! Please review the review, and see if you can detect any inaccuracies in my ideas or statements. It will eventually be posted here on Nikonains.org, and I would like your help in keeping it realistic and accurate. (if Bo and JRP approve, that is!) The current INCOMPLETE review is found at my Nikon Digital website http://www.nikond.com. Read the silly story of how I bought my D100, and let me know if you experienced anything similar. Then check out the review. I will be progressively adding to it over the next couple of weeks. It takes a LOT of time to write a review like this. When it is posted on this site, it needs to be incredibly accurate so that the Canonites cannot point any fingers at our beloved Nikonians.org!