There's nothing "astonishing" about Williams' Superman score. The shameless copy+pasting of work created for an older project reaches only one conclusion: a lack of originality and creativity in an approach to new projects. It is the same, glassy-eyed lack of creativity which prodded Singer to create an entire film living from the fumes of another work, and its poor reception was the expected response. That applies to the score as much as what passed for a script and what was trotted in front of cameras. Horner was working on a film that was part of a continuing series, yet his score was not some slavish fanboy tribute to the near universally known Courage theme at all. He--like any composer assigned to a new project--had a job to do, and that did not mean drop to the knees and copy+paste work from an unrelated production.
You can worship the Williams music until doomsday, but Superman as a concept, or music which represents him--is not chained to, nor defined by the Salkind's production (thankfully), and any aggressive attempts to bond him to it leads to something never desired by audiences and ultimately rejected, such as the Singer film.
If Gunn has an ounce of sense in his head, he will define his Superman film as an original work, not lose any sense of creativity by grafting the memory of an old production to his own.
Agreed. Williams himself never borrowed or felt the need to stitch James Bernard's powerful, unprecedented score for Horror of Dracula (1958) to his own for Dracula (1979). Williams' Dracula was specific to that film, and despite how magnificent and memorable the entire composition was, the next major Dracula film--Francis Coppola's Bram Stoker's Dracula (1992)--did not refer to it at all.
Recognizing the need to create an original score for original work is common sense. There's no mass outcry from audiences who want to be reminded of unrelated productions.
Well put. Similar to how Rupert Gregson-Williams' score for Wonder Woman (2017) was an entirely unique work--perfectly fit for a new approach to the character, hence the reason no one in their right mind was going to refer to Charles Fox's very popular theme from the '76-'79 Wonder Woman TV series in the film. Any attempt to do so would have been nothing more than fanservice completely out of tone, intent and sync with said new approach to the character, one with no connection to that TV series.
I believe that Williams' score for the 1978 Superman movie is excellent. But like you, I believe it belongs with the films that starred Christopher Reeve or any films from the same universe. Attaching this score to any other movie featuring someone else's Superman or outside of that particular universe seems like a slavish example of fan service, the nostalgic factor or worse, both.