The choice is a striking departure from the unwritten Hollywood rule of characters in historical epics employing British accents — from The Ten Commandments to Ben-Hur to Gladiator to HBO’s Rome. Obviously, The Odyssey characters speaking the various dialects of Homeric Greek, Attic and Hellenistic Koine wouldn’t make for a very accessible film. But the modern British accent is traditionally considered universally pleasing and “just foreign enough” to convey a timeless quality (even though it’s only existed in its current form for 250 years or so).
The trope is so consistent and familiar that even fantasy shows set in other worlds, like Game of Thrones, use British accents. In perhaps the most amusing example of Brit bias, the English accent was used in HBO’s 1980s-set Chernobyl rather than subjecting viewers to five hours of Russian accents (the limited series’ director, Johan Renck, rather bluntly explained, “[The Russian] accent on film is tremendously stupid”).
From the article: