First, I agree that the officer simply used more force than needed to accomplish the job. Not only does that foster disrespect for law enforcement, it risks injury to the person being arrested, detained, whatever - it's much smarter to avoid the risk.
Second, regarding Turtle's comment that schools are reversing the cell phone bans, and largely at the parents' request, I wonder whether the [very real] possibility of a mass shooting at school isn't playing a large part in their [the parents] thinking?
I don't think it's because parents want to be able to contact their offspring during classes - it's so their offspring can dial 911 if the worst happens. After the events of the past few years, nobody thinks it "can't happen" in their kid's school anymore.