1.0 didn't use the full original matte painting, 2.0 did. Look at the stone walls.
Also, even with the GOUT's odd black levels, you can see darker shadow detail in the live footage than in the matte painting. And the original matte painting doesn't seem to have any black in it (though these tones aren't exactly what showed up on film, of course).
1.0 is too bright, 2.0 is too dark; maybe the answer would be to split the difference at something in between?