There has already been a thread along these lines.
It was using SIA network method of only storing par2 type chunks and reconstructing the file. It was to store more chunks (n) of the error correcting files than the size of the original file (m) and the file is recreated from any (m) chunks.
It creates a large processing overhead for perhaps little benefit. The larger the file the multiplied time to process.
The idea of one or two error correcting “par” files would not have the same massive overhead for large files, but still be significant for creation. And it would mean that all files stored would cost more. The PUTs for the 1 or 2 “par” chunks
I suggest that an APP is used (native to computer OR SAFE APP) to create the “par” files and the user remains in control of which files to have the error correction file. It could be made to be seamless for the user with the SAFE APP doing the work of creation and rebuild if needed. The technology for error correction files changes often and this allows the core network to remain simple and the user chooses which method he wants for it.