Bob, many courses in the PNW have a similar problem. Those that have undergone a thoughtful approach to the tree issue ultimately end up where Royal Oaks has gotten. Columbia Edgewater, just across the Columbia River is probably another good example. I don't know about the other Portland courses but certainly Fircrest in Tacoma found itself in need of the removal of 360 trees. Their removal has opened areas and exposed architecture that had been lost to encroachment.
The problem is often members who fear making their course "to easy" through the opening of corridors. My own home course, Oakbrook is now 43 years old. When built, it was a fairly open prairie with stands of Gerry (Oregon White, now endangered) Oaks. Well meaning members planted hundreds of small Douglas Firs which are now overgrowing the slow maturing oaks. When attempts are made to thin the 'to easy' argument is used when in actuality the course begins to be uni-dimensional. Options for 2nd shots into greens have now become impossible resulting in tee shots being placed into one area and then the same 2nd over and over. BORING!
This alone may be the one reason that courses in the PNW are overlooked on ranking lists. Some deserving courses are simply dissappearing beneath beautiful stands of Fir, Cedar and Sequoia.