The one thing I do like about git’s staging area is that it’s truly useful for reviewing a bunch of changes (bulk actions or automated tools). Go over the change chunk by chunk and stage what matters (magit makes that extremely quick.

That could be probably done by jj. But the git’s way is already fine for me.

Yes, jj does make this very nice and easy. It’s the same idea as git, except that “the index” is just another anonymous change, not a distinct feature.