> you have formatting editors who make the PDF look good and give it a thorough last read (finding for me several errors that peer review never found - missing or switched references, for example).
This may depend on the field, but in CS I have never seen this. There is essentially no change made by the publisher to papers, and when they do make changes, more often than not it is to introduce errors.
In any case, the huge profit margins of publishers indicate that the cost of this dubious service is much lower than the charge.
But the most important point is this: doing minor copyediting shouldn't be grounds to own the journal and own copyright on the published articles. The journals should be owned by scientists, or by a nonprofit scientific society. Even assuming that research needs to pay for copyediting services, these should be contractors of the nonprofit (with competition among them), not owners of the journal and articles.