The publishers can't give up control of pricing. If a third-party gatekeeper gains enough traction they'll control pricing, by making the market, and be able to sway the consumers choices. (Think iTunes with music or Amazon with book publishers.)
If publishers work with any micro-payment system they'll be competing on a penny-per-article basis, and not be able to pressure users into paying $4/mo for what's mostly an unwanted product.
If publishers work with any micro-payment system they'll be competing on a penny-per-article basis, and not be able to pressure users into paying $4/mo for what's mostly an unwanted product.