I understand your point, but it does happen. For example, commercially available LED lighting that is more efficient than compact fluorescent. The blue LED was invented in the early nineties and you just knew it was a matter of time before we would get efficient white-light light.

The problem is that for every person who says, "This is 20 years away", there are unrealistic people who are saying, "This is 5 years away". And there are pessimistic people who are saying, "Oh, this is just going to go on for ever. They don't really know how long it's going to take".

Will you ever be able to read popular news articles and reasonably expect the predictions to be accurate? I doubt it. Are there people in the world who have a pretty good idea how long it will actually take? For a great many things, yes.