said by espaeth:
Practically speaking, however, peering of networks and getting interfaces to simply dump traffic onto a network are different things.
You're viewing this all wrong.
As a consumer I am paying Comcast for transit. They should be providing paid transit and offer settlement free peering at large at IX points (where practical). You can argue about interfaces and traffic ratios as what should be considered reasonable for a port cost (maybe 10G minimum).
They can also be selective in requirements and still be open. (eg. must peer with us in each region to avoid, route policy via MEDs, etc).
Why should Comcast feel the need to make money on my transit and then turn around and make money on my eyeballs. That's essentially what they're doing with such a selective peering policy.
One more thing, having a closed peering policy is actually makes my transit worse. For example, v6 transit often sucks for me because Comcast won't peer with HE or OCCAID directly.
Edit: Please don't make the argument that Comcast is a Tier 1 so it's okay that they have a closed peering policy. Not even close to a tier 1.