Game options files should inherit the master core settings, and override only the settings present.
Say, you want to enable the widescreen hack for a game - you should be able to do that in the game options file, without duping every other option. This becomes a problem if you want to change your master options, because you now need to trawl through every game options file and make that change, whereas if a single master set of settings was honored, and only the settings present in the game options file overrode the master setting.
So the game options file would have just one line:
beetle_psx_hw_widescreen_hack = “enabled”
All other settings would come from retroarch-core-options.cfg
imo this would be a highly beneficial change.