Iconic Press provides at least one, albeit highly unusual, example of why you might not want your publisher to register copyright.
That is Jano Donnachaidh who did register the copyright for some of the books accepted by Iconic Publishing... to himself. And in the cases that I have seen--these are not work for hire contracts, just standard publishing contracts. They give no basis for the press to hold the copyright for these works by authors including C N Howard, Tricia Drammeh, Wayne Zurl and Conor P Dempsey.
Aug 9: This Latest Publishing Disaster
Aug 21: Publisher Alert: Iconic Publishing / Jonquil Press / Red Lizard Press