I figured re-uploading could be added to NIP-96 but that's not its focus. If someone were to create another server that implements NIP-96 chances are it wouldn't have the ability to re-upload. since its not a requirement in the nip.
Blossom on the other hand requires servers to support re-uploading (uploads without modifications) and media optimization can be an optional endpoint
The requirement for re-uploading blobs is critical if we want media to be censorship resistent-ish and available on multiple servers. This is also why it has the requirement for serving the blob at the root path. this allows users and clients to easily ask an unknown server for a blob without having to get a "map" of the endpoints
I decided not to put my efforts towards NIP-96 because I think its more complicated than it needs to be and it only focuses on uploading. where as my focus with blossom is on downloading and distribution
Thanks for your interest and I'm happy to answer any questions you might have