OSC is fantastic in many ways, but it makes for a pretty inefficient (and unnecessary) replacement for the primary use case of MIDI, which is note on/off messages. It’s much better suited to some of the other layers that got bolted on top of MIDI, such as MIDI Show Control. For most musical purposes, MIDI v1 is perfectly sufficient, well-documented, optimized, and open (from the standpoint of being free to implement).
OSC absolutely has caught on in a lot of professional applications, just not the ones that MIDI was initially designed to serve. It’s huge in the world of theater, for example.
(Background: I wrote the initial OSC implementation for QLab [a theatrical show control application].)
My main beef with OSC is that there is no “there” there. It is hyper flexible at the cost of you needing to design your own meta-protocol. Like every single instrument that supports OSC has a different API with a mess of docs you need to read. Doesn’t really get me in the mood for making music.
The DAW manufacturers had a very hard time creating user interfaces that studio engineers could use to configure OSC, and I think that was a main reason nobody ever used it as a synthesizer control protocol.
OSC is awesome but it never caught on with the mainstream because nobody standardized common music production events like noteOn/noteOff or control change.
Furthermore, the original developers never attempted to build any industry consensus.
This was probably partly intentional, as it was designed by the academic community to solve the needs of relatively esoteric music production systems (e.g. [1]), whereas MIDI was standardized by a broad consortium of manufacturers of professional-oriented music products.
https://en.wikipedia.org/wiki/Open_Sound_Control