it's not white because of the glare. any way you put it spending a long time with your eyes staring at an electronic device they're bound to start feeling uncomfortable.
as far as i can tell, it's exactly the greyness of the background that makes the reading experience so effortless. that and the fact the balance of words per page is just right, not to many not too few.
actually, before getting the Kindle 3, i did not use the kindle app to read on my PC at all. i just couldn't. i did not consider it eye-friendly
it was there just so i could buy the books.
as to the newspapers, realistically, you can't have such high expectations from a 6-inch screen. a more thorough research should have led you towards the DX or the I-pad, both pricier devices, but with the larger screens.