How is that much different from a plugin system? Because now you have developers writing bespoke code with a shim for each host DAW. At that point you've pretty much developed your own modular component protocol... literally a step away from a plugin system
It's not different, and in fact most DAWs are already doing something along these lines internally to actually implement an abstraction layer that can load various plugin formats and have them all interact. That's actually my key point: it wouldn't be significantly different for users.
But there are (at least) 12-20 DAWs, each with their own (internal) abstraction designs. It's bad enough having to write (or being able to write) plugins for:
AAX, VST, AU, LV2 (at least)
Now you'd be talking about 12-20+ different "plugin APIs". That's not going to fly.
As per your other comment, it seems things are already going in that direction, if developers are treating their plugins as being written in a format that could be described as "AU that is compatible with Logic but nothing else" or something like that (substitute for any format/DAW combination that the developer wants). So I would say that in a way it has already flown regardless of how we feel about it.
