I'd be nice to have more specific settings for default downloads. Currently you can mark the downloadable file as a default for Windows/Linux/Mac etc on a high level. The problem is that the users of, for example, 32-bit Linux might get offered a 64-bit binary. Thus, there could be a secondary setting for bitness.
I'd like to be also able to offer, for example, .deb-packages for Ubuntu/Debian/etc users. Now this is not possible, because all distributions are grouped under "Linux".