The main argument for an exchange is qualitative. Do you want your bits to get where they are going with low latency, jitter, and packet loss? Exchanges are a very practical way to solve the N squared peering problem.
Speaking as a founder of a small exchange; it does all come down to money.
Quality hardware is expensive, and combining this with the OPEX for co-lo/power, etc. starts to get a bill on the order of $500/mo/gigE port. In my experience, the larger the company, the less likely they will be willing to pay anything to support a shared peering fabric (at least in my market.)
Our membership tends to be regional players who are used to cooperating already, and together start to approximate the capability of one of the big carriers. Exchange membership also jumpstarts business with larger carriers when they arrive.
I just toured the SIX last month, and I’m really impressed by their operation. Everybody has costs. I am particularly interested in what NANOG would consider fair, and on top of that whether or not a quorum would actually pay.
I am particularly concerned that the "race to the bottom" describes cost and quality, as well as limitation of new application development and deployment...
If you guys have a blueprint for a community or coop exchange that you'd subscribe to, I strongly suspect that it would happen. I'm happy to talk more about this off list with anybody interested.
NWAX.NET, est 2001
921 SW Washington
1.3gb daily max