I think we've all been in the situation where someone checks in multiple GB of images, and nobody notices just how much of a problem that is until later, when those files are properly reformatted and probably renamed.

What happens after this point, currently, is that we wind up with an extra few GB of old data sitting around on the cloud server, costing money and making everything slower as well, but this is truly data we'd never need to see again.

There are also cases where we try something out, then decide against that approach, but we want to delete specific files -- and truly purge them -- rather than having to delete entire changesets (which we can do, which is great).

This sort of thing tends to be almost exclusively in the realm of textures and meshes, but there are a few other use cases depending on your project. Raw mocap data that is unexpectedly large, and then the nice optimized version that is cut down and has a lot fewer keyframes. Etc.

For code and other text assets, it is clear we would generally never want to purge anything -- that's the entire point of scm. But for various forms of binary data, the ability to purge by-file would be a great way to allow for experimentation in the art, animation, and sound areas, while then getting rid of things that are not long-term needed.