Right now, almost 100% of existing research on growth in gravity fields is basically at 0g (ISS/Mir/Skylab/whatever) or 1g.
There are a lot of questions of what happens at 1/6g or 2/3g? No good experiments to demonstrate.
Thus the Chinese lander is testing 1/6th g.
SpaceX is likely to brute force test 38% g when they get to Mars. It is entirely possible that mitigation techniques developed for 0g are not useful or needed or effective at 38% g.
The Space Studies Institute (Via Gary Hudson, of Rotary Rocket infamy (alas)) is pushing for something they call G-Lab, an orbital facility with a control facility, at 0g and then a centrifuge at some other value.
If you are interested in this topic, there is an excellent "The Space Show with David Livingston" episode where Gary Hudson discusses this issue. The Space Show does not allow transcripts so I cannot link to anything like that, you are left with only listening.