The officer was an idiot. The driver was an idiot. It was DUI checkpoint. The whole purpose is to determine if drivers are drunk. The Supreme Court stands behind this. The officer had every right to have him exit the car, let alone have him roll down the window. Scotus even thought giving breath tests to motorists is acceptable. SCOTUS has also ruled that the police may remove drivers from vehicles during a traffic stop. So there you have it. The officer acted in an unprofessional manner. He did things He shouldn't have done. He will face whatever punishment his bosses decide is appropriate. Maybe the driver will sue him? I don't know.
As for the Nevada incident. That was ridiculous. I hope they are no longer officers. Nothing about that situation was right.
Now for the militarization of police. I don't see a police state. I see random headlines for stupid things cops do. Not everyone hired as a Leo needs that job. Some are not physically capable, some are not mentally capable, and some are unethical and down right criminal. The good officers do their best to weed out the bad ones. Sure, swat teams are used when it isn't necessary. Do the patrol guys like it? No. But most times, it is done to prevent the the loss of life. The bottom line is that as criminal enterprise evolves, so will the police. Policing can be a very ugly job. The public will most likely not like what they see. Please keep in mind that the men and women who have families at home, to whom they want to return, and have a split second to make decisions that we all have the privilege to armchair quarterback for years to come.