It is quite troublesome to find people like that with high profile cases, such as with that Micheal Jackson one that is running right now (which is why I brought this topic up, as it is seems rather like mob justice (burn the witch! He poisoned Jackson!) and sensationilism here).
Aha! That explains it. What you're seeing is an adversarial justice system. The tone you're referring to is not a result of jury trials (though they do tend to be more sensationalist, especially for high-profile cases), it's the way Common Law justice systems usually work. The US is the most extreme example, where prosecutors and defense attorneys are often at verbal fisticuffs, but in Canada the "my friend" monkier by which the prosecutor and defense refer to each other is often a euphemism for "that ****head over on the other side," as you can frequently tell by tone =P
Adversarial justice systems may look sensationalist to outsiders, but they work very, very well. Basically, the setup is like this:
1. The investigator (police, whatever) presents all the evidence, both for and against an accused, to the prosecutor.
2. The prosecutor evaluates the evidence and determines if they proceed on charges (this step has some variations depending on the country; Americans have grand juries involved too).
3. Charges are laid by either the investigator or prosecutor if the evidence warrants it.
[3.b. - depending on the jurisidiction, a preliminary hearing may occur where a judge evaluates if there is sufficient evidence to proceed].
4. Defendant is summoned to court and makes a plea (guilty, not guilty, not guilty by reason of mental defect are the common ones).
5. If the plea is a variation of not guilty, case proceeds to trial.
6. Defendant chooses trial by judge and jury, or by judge alone (depending on the crime; some do not allow jury trials in some places).
7. Prosecutor is responsible for presenting all the inculpatory (he's guilty!) evidence at trial, and has to disclose their entire cases, including all exculpatory (he might not be guilty) evidence to the defense. The prosecutor must prove the inculpatory evidence shows the accused is guilty beyond a reasonable doubt. If the prosecutor doesn't meet this burden, then the charges fail (and often the defense may not even need to make arguments if the prosecutor has not proved their case sufficiently).
8. The defense is responsible for questioning and examining the evidence presented by the prosecutor in order to show that there is reasonable doubt of guilt. In some cases, the defense may also call their own evidence to further poke holes in the prosecution's case. The defense generally does their job not by making a prosecution case appear entirely false; rather, their role is to demonstrate sufficient evidence exists to show their client probably isn't guilty.
9. The judge is the impartial trier of fact in all of this. They don't get involved in the brawl, rather they referee the conduct of the prosecutor and defense to hold the evidence given in court to an admissible and relevant standard. They evaluate the facts, make legal judgements on the conduct of the trial, and respond to motions by the prosecution and defense to dismiss and admit evidence. The judge does this in all trials.
10. The jury, and the judge in non-jury trials, is responsible for weighing the evidence given before the court to determine if it meets the beyond a reasonable doubt standard to determine guilt. If the evidence does not meet that standard, they are required to make a finding of not guilty.
The adversarial system can be contrasted to the French system (and some lower English courts involving magistrates, IIRC) where the judge is actively involved in the case and actively works on the side of the prosecution. This may be similar to the Netherlands, whose justice system I know nothing about.