In addition, it is my opinion that if the next hardfork release notes are as bad as HF26/27, nobody should take that hardfork seriously. Regardless of how well implemented the code is, if the developers can’t be bothered to write any kind of release notes for a hardfork, nobody should consider deploying it on the mainnet.

Agreed and I've mentioned it to those writing them. One thing that Steemit did properly was write reasonably good release notes for all new versions, not just hardforks. Release notes should be more informative and written well enough for people to understand. Most people still do not understand the new curation rules and that is, in part, due to poor documentation and release notes.