Many theories have been put forward to explain the recent (say 1990s onward) increase in the number of Test matches that have not ended in a draw. The usual suspects are better fielding, the dominance of Australia, faster scoring, better catching, more aggressive batting habits inherited from one-day cricket, and so on.
I'd like to think that a small contribution has been made by technology, more specifically, the use of side-on cameras to help decide line decisions like stumpings and run-outs. I do not have precise dates or numbers at hand, but I would be very surprised to find out the number of these dismissals has not increased since the introduction of television replays and third umpires. Any statheads out there that are willing to do the hard work and put some empirical meat on the bare bones of my wild speculation?
The run-out decision is a notoriously hard one, and always has been for umpires. They need to quickly get into place to make an effective call, and while this is not so difficult when the batsmen are running two or three, it can take some nimble stepping when a quick single is on. Batsmen have been given out when they were in, and not-out when they were out. (I suspect the latter was more common.) But there is also something about the nature of the call itself that makes it a hard one. Two events must be tracked simultaneously, the advance of the batsman, or his bat, towards the crease, and the dislodging of the bails, and then the judgement made which one occurred first. It sounds simple, but it can be a dodgy call when people are screaming (both the fielders, and the crowd).
Stumpings are a little easier when the batsman is dancing down the track, but the overbalancing ones and those where the batsman is dragged forward and then tries to slide his feet back into the crease are hard to give. I'm willing to bet we've seen many more stumping decisions of this kind in recent years due to the use of the third umpire.
The use of the third umpire has also affected umpires themselves in the way they handle these decisions. Very few umpires now raise the finger when it comes to these calls. Now, everyone turns to the television screens to find out the result of the appeal. Even dismissals which should have been total no-brainers (c.f. Amit Mishra running out Ponting at the Nagpur Test) are now referred, and unsurprisingly so. Why take any chances when a quick check can be carried out? Indeed, when Tiffin gave Collingwood out in the third India-England ODI, I almost fell out of my chair in surprise. The non-replayed decision has become so rare.
Of all the technological additions to cricket over the years, this one gives me the most satisfaction. The referrals don't take that much time, the decisions are correct 99% of the time, and there is no scope for complaint. I suspect umpires don't mind this particular intrusion too much. Sure, it's taken away some of the pleasure of watching an umpire's finger go up, shortly after the stumps are sent flying by a direct hit and an appeal shakes the remaining timber, but that's a small price to pay for knowing that the decision came out correctly. And that the game is one wicket closer to a result.