Mike, the successful shots from the Human Players were with a "hammer throw". It is different from a frisbee launched by a 5000 rpm spinning wheel in that it has a much higher translational velocity.
These hammer throws were traveling TWICE the distance of the field. Spectators on the ends of the field are already at a viewing disadvantage due to the goals this year, which really block the view of the gameplay.
They would not see it the disk coming at them and could easily suffer facial contusions. (the term that a lawyer would use when suing FIRST)
I was at the Suffield Shakedown and witnessed more than a few spectators sitting at the ends of the field "bonked" by a disk.
The public has not signed (nor electronically submitted

) a Consent and Release form. While an injury and attendant lawsuit at a FIRST Robotics Competition would increase our media presence, it is an unacceptable risk.
Placing more netting at the ends of the field is not impossible, but more problematic given the less than two weeks until the season begins and the variety of venues at which the events are held.
A better solution
may have been to allow the human players to throw around the feeder stations and disallowing the hammer throw. Spectators and human players would be more familiar with that style.
The GDC does not have the luxury of assessing this adjustment, so they erred on the side of safety. (As we all try to.)
Nonetheless, "what's done cannot be undone" ~Shakespeare.
Or can it? ~Mooretep