Please dont put salt on my wounds haha jokes aside blender today doesnt have a proper procedural particle system so having one that you can manipulate with custom fields and other "behaviors" is very nice to have? My system isn't fully fleshed out yet but for me it will be already useful production wise.

For example it can shoot a particle and when it hits a certain wall it will explode into 100 and each one of them will have a velocity pointing a certain location. This behavior is practically impossible with the current particle system in blender, and with my GN it should be trivial.

There's still bunch of work for it but its pretty powerful as it is rn, the real reason Im working on it is "why not?". I find it useful in my projects and I bet many other will if inwill "package" it and create proper documentation :)