Safe to say that MIDI opened the door up to a lot of would-be composers, myself included, I am sure it changed many lives for the better (and initiated GAS in many others).
My first MIDI synth was the Korg Poly61m (descendant of the Poly6). I purchased a Poly 61 (no midi) in 1982, and then when the M was released, I switched over to that. You needed a midi filter box as it received only in OMNI mode! Next was the Prophet 2000.
Those were the good old days in some respects, my studio partner back then purchased a ton of midi modules, we had 4 Yamaha DMP7 mixers cascaded together, every parameter was automatable by MIDI, and more keyboards than we had room for.
Now its all in one little box. (Thank you Steinberg for VST). But I still have some outboard gear speaklng MIDI.
Happy Birthday indeed.