As this earlier post suggests, the ideal of blonde beauty wasn't invented in Hollywood. Good luck finding a brunette Virgin Mary or Venus in a Quattrocentro painting. (Mary Magdalene generally has red hair.) But until yesterday, I didn't know that the blond ideal extended to Donatello's David.
The two versions of the statue raise an interesting question about authenticity and copies. Nowadays, it's possible to make a perfect copy of a statue in bronze. So which is the more authentic version of the original? The one that looks the way Donatello intended the statue to look, or the one he actually worked on? As a matter of both modern taste (that gold is a bit much, at least under electric lights) and history, I prefer the original. But I also like seeing them together.