You have a group that runs fiber+dwdm+sonet(or SDH). You have another group that runs IP. When the IP guys ask "please tell us how the optical network is designed, and can we coordinate how they're built and btw, we want to put DWDM optics in our routers", the answer from the fiber+dwdm+sonet group is "no, but we can help you with transport using our transponders, please just order circuits, just give us addresses for each end and we'll take care of things, don't you worry your little IP engineer brain how things are transported long distance".
I believe this is still the case at a lot of ISPs. Not all, hopefully not even most, but I'm sure there are some.
you underestimate the extent of the dogged determination of circuitzilla to hang on to the fiber with her/his fingernails. randy