> I guess the reason is probably that it probably requires a developer with a midi device That is not true at this point. AFAIK Windows, OS X and ALSA all supp

> I guess the reason is probably that it probably requires a developer with a midi device That is not true at this point. AFAIK Windows, OS X and ALSA all support virtual MIDI devices. Windows and OS X (last time I used it) ship with virtual General MIDI outputs and there is a lot of free third party software for virtual input. I'd rather say that the reason is probably that you need a developer with domain knowledge and interest, and a consensus on what the standard should include.