Actually, Bill, MIDI first started as a collaboration between Dave Smith (of Sequential Circuits) and Roland, with Dave doing most of the initial work. They had a fair amount of it figured out before it went further than that, and got the other manufacturers on board (and some like Oberheim, were quite resistant to the protocol, preferring their own proprietary system for quite a while). It was by no means collaborative between all the manufacturers, simply delivered in their laps for them to approve, and amend, on the whole. The MMA is a large, slow organization, with few of it's members even making arrangers, so probably little incentive to work quickly.

Also, you have to understand that the vast majority of arranger sales come from just the Big 3. I would be unsurprised at maybe 95% of all arranger sales come from those three, so getting them to implement this would make it a de facto standard.

The thing is, the MMA set standards for NEW MIDI codes, but this problem is solved by existing ones, and is, in fact already essentially solved. The system exists, it only needs to be implemented.

Trust me, the MMA has been discussing HD-MIDI for years (decades) now. Do we really want to wait that long for something that already exists?