Photos will not and t is not stupid at all - it is required by the database structure -
It is not really required by the database structure, Larry, as long as the photo application is doing the renaming, and safely. Apple has shown that in Aperture, where we had many file naming presets. It was easy to batch rename the originals, when importing them to Aperture, or later, using the batch change commands. Aperture could keep track of the changed filenames, since it did the renaming itself.
Now we have to import the photos twice - first, to export them with new filenames, and then to import them again with the new filenames. This is very wasteful with an iCloud photo library, where Photos will start the upload to iCloud immediately after import and we have to wait, until all traces of the first import will have been removed from iCloud, before we can reimport the renamed image files.
Being able to change the filenames is necessary for the share options in Photos, for the simple reason that Photos is letting us only share the filenames with the photos, if we are using Photos's built-in share commands, not the other user added meta data. The titles and descriptions, the keywords will be stripped, when we are adding photos to a Shared album or are mailing it. All the recipient will see is the filename. So we have to take care, that the filename carries as much information as possible, if we ever want to use the building-in Share commands. Apple could make sharing from Photos easier by providing tools to change the filenames or by providing other ways to share photos with user defined metadata - captions, titles, keywords.