weekend observations

I tend to agree with your observation based on what we experienced on our six week long trip this past summer. There was a lot of extended stay units in most of the parks we visited. And as noted, in several but not all, the extended stay folks had the prime spots. From an owners perspective, it makes good business sense to rent to extended stay campers versus overnighters. That gives them a steady revenue stream and takes fewer man hours to take of the extended stay campers' needs.
This trend just means that there may be fewer impulse stops on our travels and more reserved overnight spots. But we will adapt and do whatever it takes to continue our travels.