The previous point (an unforced error) he bounced his racquet twice on the ground (right in front of me). In days gone by, the umpire would have fined him a point for racquet abuse. This might have either immediately controlled his anger, or driven it deeper. But he would NOT have reacted in the way he did after he lost the following point - which was actually a really well played cross-court from Cilic.
There was no alternative except to disqualify him. The crowd hated it because they wanted to see good tennis. But to have gone on to win the championship having injured a line official would have been totally wrong, so they were unfortunately right to call a halt to the match, even though they might have prevented it happening by reacting to his previous tantrum more decisively.
Then came the BBC on-court interviews. First we heard a disappointed Cilic who clearly was embarrassed to have won the championship in this way. Then the interviewer, Sue Barker, talked to Nalbandian. First he begrudgingly apologised to 'the guy' and stated it was a mistake. No shit. He'd given 'the guy' a deep gash from which blood ran onto the court. Immensely painful I would imagine. Hopefully the shin bone wasn't damaged. I hope he sues! Then, to Nalbandian's eternal shame, he began a rant against the ATP for putting so much pressure on players (making them play too much, too many rules etc) to the point where losses of temper were inevitable.
Well tell that to Roger Federer, Rafa Nadal and Novak Djokavic. Everyone loses their temper occasionally on court, but they never exhibit violent petulance. They're all under the same (possibly greater) pressures, as we all are in one way or another, but to lose control and then blame it on the system, in my view, defines immaturity.
David N - if you don't like being paid to perform within the rules of the system - find another job! I gather there's an opening for a line judge...