Just dug through the ML archives. This is the thread I had in mind http://lists.wikimedia.org/pipermail/commons-l/2008-October/004235.html
The image quality, which was unimpressive back then, is by todays standards even more ridiculous. The images are on the level of sub-stubs. Flooding commons with hundreds of thousands of low quality images, just because a few hundred maybe even a few thousand are potentially interesting for articles is a _waste_ of resources. And by resources I do _not_ mean disk space, I mean valuable resources like contributor time (all that stuff will have to be categorized too). We are not doing a service to our users either if we essentially spam our category pages with tons of those images, drowning the good stuff that we have.