So, I honestly don't get what's sticking in people's craw here.
Shakespeare, last I looked, mostly wrote fiction.
Even if they made Henry IV or Henry V or Richard III black, I wouldn't be outraged. Joel Coen made Macbeth black in his recent movie adaptation.
Patrick Stewart starred as Othello in a race-swapped production in the 90s.
Last I checked, Tom Holland isn't Italian himself.
Hypothetically, if the director were stupid enough to cast the entire Capulet family with white people, and just left Juliet to a black actress, the decision would be worthy of mockery. Still, that mockery should be directed at the director, not the actress.