Micropayments

This article is interesting. There have been numerous schemes over the years that have been designed to facilitate micropayments, but none of them have taken off.
Quoting the article:

Amid the disdain, and without many people noticing, micropayments have arrived — just not in the way they were originally envisioned. The 99 cents you pay for a song on iTunes is a micropayment. So are the tiny amounts that some operators of small Web sites earn whenever someone clicks on the ads on their pages. Some stock-photography companies sell pictures for as little as $1 each.

“Micropayments are here,” said Benjamin M. Compaine, a consultant and lecturer at Northeastern University who specializes in media economics, “they just have not evolved in the way that everybody expected.”

Why do you think they have "not evolved in a way that everyone expected"? Do you think micropayments will continue on their present trajectory, or do you see big changes coming?