I think FF could shift to a whole new level of awesome with this.
I would like to have a proper C# API for programming new nodes along with a plugin system for adding and using the new nodes. I think doing this would allow for FF to be expanded in ways none of us imagined before.
Grasshopper3d is the greatest example of what can happen when software such as this is unleashed with expansion options such as C# node creation. It now does things with plugins it was never specifically intended for but users adapted things to it and expanded its reach because of that. It's become a viable option for people working on many different types of things that would have otherwise never given it any notice. In essence, it's not only enhanced the offering and the capabilities of the program but drawn in new customers they never would have had otherwise.
Blender is another somewhat similar example with some obvious exceptions and differences. Still, the core end result for them has been that the users have broadened the functionality with new nodes and given the whole user base more options to do more things with the software. For a time a while back there was even a group working on replicating all the FF nodes into blender nodes. But, I think they got stuck on the graph functions and fell apart after that
Another consideration for this idea is that as a commercial product FF is more restricted through licensing than end-users for adding functionality from outside libraries and other resources. Thus this could allow FF to be expanded by its users with features and things that would otherwise be out of reach or infeasible due to licensing restrictions or costs.
Looking through the feature wishlist forum reveals a lot of requests for various nodes and functionalities that this could allow for making and fulfilling. So, in a way doing this would also sort of knock all those requests off the board too. Along with any other similar future requests for things that could easily be made through this and by that time may have already been made by users. In that way, this one request handles potentially hundreds of requests over time
Also, maybe this is more of a request for an SDK than an API. Not really sure offhand.
Anyway, I think it's at least worth looking into. My understanding is that FF is C++ so a C# API for making new nodes and plugins should be a possibility I would think.
Thanks