In America stats show otherwise so your point is moot.
America also is not a homogenous society. There is an intrinsic value in having a diverse school environment it leads to a cohesive society. I really shouldn't have to explain that.
There is no evidence that diverse schools are better, any improvement by black kids going to a "diverse" school can be explained simply by them going to a better school. And the fact that black kids going to black charter schools show improvement shows that diversity isn't the key
There is nothing wrong with wanting diversity, there is something wrong with the government violating individual freedom to achieve it and there is something wrong with diversity being the actual plan to improve black education
The only plan for black education that has shown to work are plans (and schools) that address culture