I think it's an extension of trying to avoid the effects of "conviction in the court of public opinion". Imagine seeing a coworker on trial on the news.
Or imagine being on trial, declared innocent, but most people just saw the fact you were on trial and recognize you by your picture.
There's also details like having the jury's faces be out there.
Personally I think a lot of this is "solvable", and having video footage in places like the supreme court would make coverage of it a bit easier for places like TV. Say what you will about TV dumbing things down and only taking fragments, having more people pay attention to the judicial system would be a net positive IMO