There needs to be some sort of combination between subscriptions and "pay as you go." I pay for The Washington Post, since I tend to read it almost every day. I won't pay $4/month for Wired, since I'm not a regular reader. I'd pay say 50 cents an article, though, if that were an option. That goes for The Economist, Scientific American, and a number of other sites.
The main issue with this type of payment model isn't the money; it's the mechanics of it.
If something behind the scenes automatically took my $0.50, kept track of the fact that I was entitled to read it on any device and browser I might use anytime in the future, and didn't bug me about it ever again, then it might be workable. I don't have a problem paying a few cents for an article. I have a problem manually entering into the transaction to pay a few cents every time I want to read an article throughout the day.
