> if their research is so important Because it is not. US tenure positions are already saturated with far more applicants than available positions.

> if their research is so important Because it is not. US tenure positions are already saturated with far more applicants than available positions. There are still a lot of top tier chinese professors at US universities. But, the US is skimming the cream of the cream of cream. Some inevitably fall through the cracks. Also, US universities expect their profs to teach. I know for a fact, that grad school rejected professors for not having adequate English proficiency for teaching. These same people probably excel at teaching in Chinese back in China. It is also a culture thing. Sometimes US universities want to recruit talent that fits in with their culture. Sometimes, bad culture matches for US universities, might just be good culture matches for Chinese universities.