God has spoken. We'll see if it's in place for 2014 in Brazil, but what the FIFA president wants, the FIFA president gets. That being said, I obviously applaud this move. This blog has repeatedly praised efforts to automate officiating as much as possible to remove the "human element". Not because referees are unnecessary, but because questions like "did the ball cross the goal line" do not rely on human judgment.
So while we're discussing lines being crossed, what is and is not an example of when human judgment is necessary? Well as much as I bemoan the subjective nature of soccer and basketball officiating, even I admit there are situations where you can't have a bright line rule. An example is an aggregated yellow card. Normally in soccer you get a yellow card for an egregious foul, such as tackling someone from behind when the ball has already left, or throwing an elbow up and catching someone in the head when you jump for a header. But (confession time: I didn't know this until recently), you can also get a yellow card for accumulating multiple minor fouls. Fouls that by themselves are not card worthy may get you a card by the 3rd, 4th, or 5th one.
This is a good example of when human judgment comes in. It's a good safety valve for those times when one player hasn't just completely gone off the rails, but is still quite clearly being a dick. Then again, even those minor fouls have gradations. Is this your third time committing the exact same type of foul (kicking a shin and whiffing the ball)? Or do you have three different fouls of different types? Maybe you kicked a shin, then gave a forearm shove, then maybe some mid air collision while you both went for a header. I'd say the former would be a better candidate for a card (you keep doing the same thing after being told not to), but the latter could be a situation where "okay, accidents happen when you're playing hard, but seriously, your 4th foul of any time is getting carded."
Another situation, again sticking with soccer, could be handballs. If you intentionally block a shot with your arm in the box, it's a red card (expulsion) and a penalty kick. If it's incidental (shot's coming right at you and you try to turn aside and the ball just happens to shank and hit your forearm) then the rules allow for other resolutions, such as a penalty kick or a free kick without a card (or even no call at all if the attacking team retains possession and the ref feels that stopping play is unnecessary).
Again, some things are boolean. Like a light switch, they have only one of two possible states. On/off, true/false, present/not present. THESE are the things for which we want technology and to eliminate the human element. Either the ball did, or did not, break the plane and result in a goal. And in a low scoring game like soccer, we absolutely positively HAVE to get that right.
Other things have shades of grey. Machines can't measure intent, nor can they assess moral value. Is that 3rd foul too much? I'd say no if each foul were different, yes if it were the exact same. Were you trying to put your hand in the way of the ball? Machines can't weigh circumstance. David Hume once spoke about the moral sense of human beings, and to completely oversimplify his thousands of pages of philosophy, let's just agree that human beings can look at a situation and say "that just doesn't seem fair". Machines don't have that capacity, but we do. Life may not be fair, but one of the reasons we watch sports is because we expect THEM to be. And while universal application of the rule set as written is the best way to ensure the literal playing field is as level as possible, we need that safety valve. Technology in officiating protects the game's integrity from corruption, bad decisions, and ultimately the short comings of human physical senses. Human judgment can be reserved for protecting the players from the machine's utter lack of moral sense.