Ha, if you honestly think kids are going to just casually walk balls back to their loading zone, you didn’t see the hours of athletics training kids put into figuring out how to throw pool noodles 40+ feet.
I expect to see full field throws, possible into a net of some sort if not specifically disallowed.
I only see this being a thing if teams can get the balls to land into a corner of the field. Otherwise, I don’t see the consistence being there. Even if the consistence is perfect, you have to worry about the balls hitting themselves on the ground. I don’t see that being very viable.
Even if you can build a shooter that is super consistent, you have to shoot slow enough on a 2d goal that balls don’t hit each other in mid air. Maybe not a huge thing, but something to consider.
I see the 3d goal being a better option for those who have it. Creating a consistent cycle out of a loading goal makes a lot more sense than the time it will take to try to perfect a shooter. Someone will figure out how to create the cycle in the 2d goal, but it will be 2 or 3 teams, not hundreds.