Economics and financial transactions work well with fairly evenly paired buyers and sellers, and largely undifferentiated goods (bulk items, water, food, etc.). Where market power is unbalanced, you end up with monopolistic or oligopolistic markets, where goods are highly differentiated (think: enterprise software sales) you end up with very prolonged negotiation over quality and deliverables (hence the high cost of such sales).
Information economies violate both precepts.
We've never had a market for unbundled information goods purchases. A newspaper or magazine is a bundle of articles, a book is a bundle of chapters, cable TV is a bundle of channels. Most entertainment parks sell a bundle of rides rather than tickets to spend on any given ride. Even music and video sales are a very different experience when you can sample and preview what you're getting.
If I had to make a purchase decision for every single thing I read, I'd go stark raving mad (OK, this may explain something).
Commercializing every single transaction is not feasible.
It's just a matter of time before it does. I'd rather say the current micro payment offerings are not good enough.