I would not totally discount the utility of the 3 inch LCDs on the newer cameras. If so, all of us can just do with the 1-2 inch LCD screens or even throw it away all together and just shoot ala film. No doubt the histogram is best for exposure verification, the resolution and the colour accuracy of the LCD screen is actually essential for checking focus and for white balance respectively while in the field.
For example, on the E1 LCD, the screen is so small, and the resolution so poor, and the zoom range is limited. For that reason, it is not as easy to check how sharp the image is compared to on the newer cameras. Of course, I usually trust the camera and more than 90% of the time, the images are sharp although there is no way I can be 100% sure based on the LCD screen.
Also, if u shoot RAW, u may think that WB is not an issue and colour accuracy is not so important. BUT, if u want to have your photo come out with accurate colours as is, you may not remember exactly how the colours were supposed to be when you go home and start processing your RAW files. Hence, in situations where u want to have total control of the WB, u need to have an accurate reflection of the colours on your camera LCD....and this can only be done using the camera LCD in the field...unless of course, you can bring out our PC or laptop and shoot tethered. So it is recommended to shoot RAW+JPEG in these situations.
Maybe you guys are not aware, but on the EPL1 and E5, you can calibrate the camera LCD screen by adjusting brightness and temperature. I think this will help to make sure that what u see on your camera LCD will be as close as what u will see on your PC screen (which should be calibrated BTW).
In any case, I usually set my preview to 0 seconds on my cameras. So I once I have dialed in the settings for a given shooting situation, I do not bother to check every image. I have the camera setup in a way where I can trust that once WB etc are set, everything should be OK. There are number of advantages for not routinely showing a preview. This includes faster speed (esp EPL1), saves battery life, and finally, you spend more time shooting than chimping. U chimp too much, u can miss opportunities. After a while, u bond with your camera and the camera is an extension of you, and u have to learn to trust it. U cannot be checking on it all the time.