What I´m trying to say it´s that making the API open doesn´t mean all architects must start programing, but that those who can o want to can do it easily for the benefit of everyone. Right now someone, architect, programer o whatever, that thinks can make a plugin for Archicad for some task has to pay 500€ upfront just to look around if it can be done.
That guy that had a great idea but did nothing because the dificulties Graphisoft puts on his way could had made a little beatiful program and sell it - or even launch it for free - for you to use.
Look how many applications are out there for revit. You can look its API just on the web https://www.revitapidocs.com/
, no registering, no fuss.