The idea of simply mounting a filesystem and selecting from a list of titles which roms to download and add to your local games, unloading them and transparently re-downloading when you need to free up space, all without relying on a centralized host even for the file index, is pretty appealing. You can do similar things with torrents but it's not quite as "natural".

Most of the emulator frontends I've seen are pretty against integrating this kind of ease-of-piracy stuff, though, accepting recognizing and filling in metadata for well-known roms, but not making it easy to integrate with remote libraries of roms... except tools that run on "hacked" consoles, which seem to love just giving you a list of games with a "tap A/X to pirate" UI.

Maybe fear of Nintendo coming to bite you?