… thus making it almost impossible for them to get a fair trial.

I don’t know about the USA any more, but here in the UK we still have this concept of “innocent until proven guilty”. There’s a lot of evidence to suggest that any juror who has seen media pictures of a defendant in handcuffs is far more likely to vote “guilty”, because they have a mental model that says “this person is a criminal” even BEFORE they hear the first word of evidence.

So, good for media relations, good for “securing convictions”, pesky in that some of those convictions later prove to be bogus, the real criminals go free, innocent peoples’ lives are ruined, and the taxpayer picks up the compensation bill.