I guess one of the concerns it the definition of peer. The policies as
I read bhem by cnw and uunet seem to be so overly restrictive that none
of the newer carriers will meet them. I've litterllly, not from uunet
and or cw but from other carriers received responses to peering requests
"Well your to small to peer but we have great transit pricing in the
areas you requested." This is after I offered to meet them at the three
east, west, and central mae's, a coupee if diverse paix's, and Chicago.
If the concern is economics than peering ss much as possible and in a
less restrictive manner makes the most sense. The target here is to
provide the best possible service to customers which certainly ocould be
other carriers, but are most likely more other end users. If
performance is better it will in many cases be an easier sell. More
than a few times prospective customers were very concerned with peering
and interconnection. But then again I was up against uunet in a play to
get a customer and uunet promised this customer they could globally
route and announce to its peers /30's or longer. 
I certainly
couldn't make such claims. I'm mentioning this because it seems in all
companies, not just uunet claims are maid but frequently not backed up
by technical good sense. I guess its like most things there are many
approaches and certainly not everyone will agree to each approach.
I just can't see cases when not peering is better assuming the basic
requirements are met to insure proper technical performance.