What are you basing this on though? Yes, Chinese society as a whole is more racist than the west's, but people in the west don't get how divided Chinese society is: there are still hundreds of millions of peasants who will never go to the cinema (and who have never seen a black person in the flesh), and it's fair to say that's where most of the racists are concentrated. Not to mention the huge generation gap; the difference in attitudes towards race, sex etc. between a Chinese teenager and their parents is often more like the difference between you and your great-grandparents.

And I just think it's strange to complain about racist Chinese people not wanting to see films with black leads, when the US doesn't make any such films anyway. Where exactly are these films they're refusing to see? Considering only blockbuster action films (ie. films aimed at young urban males, the most progressive part of the population who all love Kobe, LeBron et al) make it into China due to restrictions, and considering that the only recent such films I can think of starring black people are TFA and the Furious films, I don't see what the evidence is.

Surely the primary burden is on us Westerners to promote black stars in the first place? If, say, Michael B. Jordan turns into the next Will Smith over here but Chinese people refuse to see his films, then we can turn around and criticize them. But right now it just seems like the criticism is coming from fanboys (not you personally, but in general) lashing out because the franchise they've loved for decades isn't as loved by people who only became aware of it a few months ago.