I think Gen Mattis' point is the fact there at this moment there is noone talking intelligently, trying to bring the country together. The rest is a given. No Gold Stars for stating the obvious.
I am in the US and we have a lot of people of all backgrounds that can talk intelligently to this moment but of course they are nowhere near our oligarchic government.
And it goes back way more than 100 years. The violent policing of black bodies goes back in an unbroken line to the English colonies who introduced African slavery. White society accepted the brutalization of black bodies. Even the Quakers had black slaves initially.
The point is rather than pontificate, which we can all do, who is going to do the hard work of leading us? Because the majority of people here agree with the protesters and disagree with Trump (plenty of polls show it). The country wants radical change.