I think the last paragraph of the linked article has pointed out the most important issue here:
Of course, what can be difficult to deny is the missed opportunity the casting of “The Legend of Monkey” to aspiring Asian-Australian artists who would have made the new show at least closer to home. With an abundance of talented Asians out there, this show’s casting could have been done so much better.
This is downright ridiculous. This is a Chinese story about Asians journeying to the West and instead they cast people from the West.
More accurately, "the West" refers to India, which's (south)west of China, in the story.
Next thing you know we will see a Warring States of Japan movie and see Jeremy Irons as Nobunaga Oda, Matt Damon as Yukimura Sanada and Tom Cruise as Ieyasu Tokugawa.
Well, Cruise did play a samurai in the past, tho that character is really a Westerner. lol