> Given what we know about statues in the classical world, and the way hieroglyphs look, it feels like a safe assumption to make that the pyramids were sporting some artwork.
>How can you not mention egypt's own royal tombs, which were chock full of rich artwork
This is actually an interesting point by people who argue the Great Pyramid is not a royal tomb...all other royal tombs are richly decorated, whereas the chambers in the great pyramid are noticeably bear.
I always understood the white polished casing stones were not painted but did have carved hieroglyphics (I think this is how they have identified some of the reused stone in mosques for example). On the other hand, the Sphinx still has some blue and yellow paint on it.
I find the "it's not a tomb" argument needs some work. If we also consider the other pyramids were all tombs, and that there is evidence of undiscovered rooms in Khufu's pyramid (scanpyramids project and others) then it seems pretty weak.
It could be something as simple as men going out into the harsh Egyptian sun more and women being discouraged to do the same.
In parts of Pakistan at least (where I was born) there is this sense of fairness of skin being a desirable trait (goes almost without saying that it is not a belief I endorse at all). I can imagine such unrealistic beauty standards echo through the centuries.
How can you not mention egypt's own royal tombs, which were chock full of rich artwork (somewhat we know because several KVs still have lot of artwork) e.g. https://en.wikipedia.org/wiki/File:Egypt.KV62.01.jpg in KV62, which is considered "modest wall decorations", or https://en.wikipedia.org/wiki/File:Egypt.KV43.01.jpg from KV43.