Sam I'm going to mix some speculation with memory. I believe the COE ramps were built, or most, before the lake filled and while the trees were being removed, etc. The lake did fill unexpectedly, if I remember right, which left a lot of private ramps short, because they weren't completed or thought of at the time.
There wasn't a great deal of interest in TR when it was built. The hiways from Tulsa, KC and STL for instance weren't exactly great and were 2 lane for the most part. My memory of TR is that it developed slowly for a long time.