1. I think there's virtue in limiting the modification --as opposed to the reproduction-- of works for some time after the death of the author. There's something distasteful about thinking of (to the use OP's example) Winnie the Pooh merchandise at Target, or The Winnie Pooh Movie having nothing to do with the "real" Winnie The Pooh. There is some value to the "sanctity" of a work IMHO, for some time.
In other words, avoiding the "dracula-ization" or "frankenstein-ization" (read: "gross commercialization") of works for some time.
That being said, it makes sense for the original, unmodified work, to enter the public domain. I think this is a distinction worth exploring.
2. More controversially, there are some works where there's a credible argument that the author is a "corporation." An example here is the Marvel Cinematic Universe. Each movie has the imprimatur of the director, but in the aggregate they feel very much "MCU" in style. If anything, the authors seem to be Kevin Feige, Louis D'esposito, and Victoria Alonso.
The characters were originally created by Stan Lee et al, but if Marvel Studios were to create a new character (and make that character a flagship one, etc) that character would genuinely be a corporate creation.
Would love a discussion on these topics.