On one hand, I don't see the point. As someone mentioned in the OP, we already know plants can survive 0G, and I really don't think there's a reason to do this experiment outside colonizing the Moon.
I don't want the Moon colonized. Mainly because what I actually do want is to fix the problems down here, and I don't think the solution is up there.
There's also a more "religious" reason for me because I admire and feel conected the Moon a lot. It already pisses me off that people went there and left a bunch of trash, and I really don't want to see a bunch of rich assholes going there to live or worse send workers to bring the glorious extractivist capitalism to it's surface.
The Moon is sacred for a lot of people on Earth, and it makes me crazy that the first thing people did when they reached there was putting the flag of one of the worst empires in all history. This isn't my main argument because is very emotional for me, but it just feels wrong.
I generally agree with all of that. Here's why I like lunar habitation though.
The moon, I think we can all agree, is awesome. It's mysterious and powerful and a source of spiritual strength. It's also unique in that unlike the sun or metaphysical spaces like heaven or the underworld, Luna is perhaps the one ancient, spiritual celestial power that happens to be a real, visitable place. You can't visit the sun or make a pilgrimage to Valhalla, but it's possible for people to journey to Luna. And we need to contend with what this means.
In my opinion, it means that it should be a place anyone can go, and it should be recognized as a cherished element of the commons, as high as any world heritage site. I don't want to see the moon locked away, I want it to be accessible and cared for. I want people to be able to go there and see an Earthrise, and get to feel what visiting Luna is like, with rules in place that demand that visitors honor her. And developing local oases of grown food and recycled air seems like a key part of that.