A reader writes:

The problem with micropayments is that users hate them, probably because they don't want to continually make a decision about whether a not a purchase is worth making.  That is why many systems that used to use micropayments, like Internet usage (remember hourly fees?), have moved over to simpler pricing schemes.  The things that still use micropayments, like utilities or toll roads, tend to be monopolies that (1) do not turn much of a profit and (2) are disliked by the people that use them.  To put in some realistic numbers, if the NYT charges about $10/month for ~100 articles, do you really want to make the judgement call about whether any particular headline is worth a dime?

Another:

Way back in 2000, Clay Shirky predicted that micropayments wouldn’t work way, and I’m pretty sure by now he is right or somebody would have done it.