What's the point of building an archive without letting everybody download the software?

The site’s copyright policy says that images won’t be made available without the authors’ permission. However, collecting images in advance of getting such permission means that:

a) disk image files are not subject to the degradation of old floppy disks. With a central database, we have a record of which programs have been imaged and which are still vulnerable.

b) the better-populated this site, and the more enthusiasm shown by its contributors, the more likely it is that copyright-holders will grant permission for their programs to be included. And if an image was already contributed, it can be made downloadable as soon as that occurs.