The problem with the old black was that there was as black as it is possible to be, meaning the game is unable to darken it to produce a gradient to make the units look real and 3D. Take a look at a red serf:
The game takes the brightest red
colour and then darkens it to produce the parts that are in shadow. This gives the serf a nice 3D look (more noticeable when it's not zoomed this much). The trouble with the old black was that there is no way to darken it:
So there is no depth to the sprite and it no longer looks 3D. The black parts just look like empty holes in the sprite. Freddy attempted to change that by lightening it slightly:
Now the game is able to produce more than one shade of "black", so there is 3D depth again.
I agree that "pure black" is nice, but the sprite does look better with depth. Hopefully this clears up any confusion about why it was changed.
IMO the fact that it's not pure black now is not noticeable unless you compare them side by side. To me the horse/swordsman in Freddy's image looks black, it does not look like dark grey. Seeing Freddy's colours on their own is confusing because the game generates several colours from the "base
colour". So you should only look at the screenshots when comparing them.
For what my opinion is worth, I prefer the "golden yellow" in Freddy's first
palette (
here) over the "green yellow" in his second
palette (
here).