We don't really know the full story. Just to try the other side here, we don't know what else she was doing when she was refusing to sign the ticket. Was she yelling, waving her arms around, trying to drive off? The officers obviously felt a need to remove the keys from the ignition. Something else was going on. It's easy for the news to just say "she refused to sign the ticket".
Believe it or not, most officers don't go looking for trouble. They would rather just give the ticket and be on their way. And having three officers at a car stop isn't so uncommon. The first officer has the car pulled over, and maybe a 2nd pulled up behind because there was a traffic congestion issue happening. Sometimes people request a supervisor, so the Sergeant drives up. Or, the officer called for backup when she started to get out of control, and 2 units showed up because they were close by.
People are so quick to blame the cops. Unless you see what they put up with every day, you never really know what is going on.
With this being said, they could have been totally out of line. I'm just trying to offer up another side.