If it's impossible to fit a bigger screen, you would think it possible to make it so you could plug in your iPhone and use that screen or something like it.
Kevin.
It's not just the phase lcd screen, well it is the lcd screen, but there is more to the story.
It's also the in camera preview which doesn't seem to apply noise reduction or a preview file big enough for detailed viewing. Shoot a peethirtyplus at 800 iso and look at the lcd, it looks like a snowstorm hit it.
Digital backs are very computer software dependent in producing the preview to the final enlarged image, unlike dslrs that do a lot of pretty fantastic in camera processing.
It's also not the size of the digital back, because a Nikon D90 is probably smaller than any phase back and has live view, in camera processing, a 3" lcd, shoots video and has a battery not any larger in physical size than the phase battery, but last forever.
DSLR's have progressed leaps and bounds and the cheap Nikon D90 is very close in final image quality to a Canon 1ds, maybe even the 1ds2 all for 1/7th of the price of a top end dslr, 1/20th the price of a medium format back.