If your trying to play the game quickly then there is no point in listening to dialog in the first place, which pretty much negates that as a point of argument for making this a feature. If your in such a rush that the fraction of a second it take to right click to skip already heard dialog then maybe you need to learn to budget your time better.
"No man can be a pure specialist, without being in a strict sense, an idiot."
- George Bernard Shaw
"Remember, every time a April Fools joke is played, a point-n-click adventure game concept is killed."