Being a supporter allows you to download beatmaps at in-game when someone uses the /np command or when you're in a multiplayer room. Having an extra key command is pointless for these two points. While you're in the title screen you easily can click on the right the osu!direct field or press 'D' to open. I actually thought this was a request to add the ability to change the keybind to open osu!direct but.. well, it doesn't.
Marking as invalid.