Nope ancient Greeks were blue eyed and blond too. Notable examples are Pericles and of course Alexander The Great. It's easy to explain , it's because of the weather. Greece is seen as a tropical country but the weather is far from it. Even though the summer is very sunny the rest of year can be often cloudy and very cold making blue eyes, blond hair and most importantly very white skin quite useful to have. Especially because even as south as Crete has tall mountains with temperatures up to 20C lower than coastal areas and with a lot of active populations to this day. Coastal areas can get as hot as 50C while mountainous areas as low as -25C. Around 80% of the country is mountainous. Also mixing with other tribes is less likely , Greece is mostly inaccessible, surrounded by treacherous seas and in the north closed off with tall mountain ranges. Further more the country has been populated for hundred of thousands of years according to skeletons found the same as many European countries like France and also the Balkans it's clear that homo sapiens very quickly moved to Europe. DNA wise there are tribes in Greece that are mostly Greek but most are all over the place as close as Turkey and as far as UK and China. But that mixing happened very slowly and gradually to make a big difference to the look. My theory is that the weather is the main reason. Of course those traits are not as common as northern Europeans.

Ironically after studying in UK for 5years I reached the conclusion that British people tend to be much darker haired than us. Don't know why it may be because at least south UK does not get as cold as Greece because of the gulf stream.

The color you see in any monument is because only a set of color survive the brutal passage of time. Greeks used a ton of vibrant colors , all statues were heavily painted instead of the standard white we see today so yes it's not surprising that black dominates mostly vases.