On television we've had a half-Japanese actor play Superman and a half-Chinese actress play Lana Lang.
This really isn't the same. Lois being African American is a significant change given the history of the character.
It is, but it would represent something different in a film set in 21st century America, IMAO, than it does in - for the obvious example - the recent stage revival of the 1960s Superman
musical which was set in the 1930s.