I doubt any officers think that it's wrong, but most are no doubt aware that this thing that is making their jobs easier is unpopular with the public and likely to be barred by courts when challenged. Best, then, to keep it as quiet as possible.

This, absolutely. The police have a dim view of virtually every restriction of their powers. And that makes sense. The police know well that in the overwhelming majority of the situations they work in, society wants and needs the police to intervene. They're spending all day locking up bona fide criminals, and, in urban areas, worrying about getting shot.

And all that means is that the police shouldn't be left to regulate themselves. And, they aren't.

Wrong (morally) isn't the problem. It's that it's illegal, and they know that. Law enforcement operating above the law is not law enforcement.

Food for thought - all law enforcement operates above the law. They all intimidate, kidnap and assault and some of them even kill. A law enforcement officer who operates within the law wouldn't ever raise his fist.