Well John, I can't explain it. Why would such highly educated people stay in a cult that is constantly dumbing down their educational content.
The psychology of such a thing is difficult to understand.
Mind-control and manipulation work on even highly intelligent and educated people, just not as often.
That being said, your area seems unique. I was in the cult for over 30 years in southern California, serving as an elder for about 20 years. During all that time I only met two other JWs that had a college education. One was a lawyer and the other has a PhD in psychology. Pretty much everyone looked down on the person with the PhD, making snide remarks about her ignoring the direction of the FDS.
This was while I was attending university to get my BA in Education. It was during that time that it became increasingly obvious to me that I was in a religion that lacked academic honesty and intellectual rigor. As I began investigating I started uncovering things such as the UN/NGO scandal and the pedophile problem. The house of cards started falling pretty fast after that.
So how could it be that there are so many highly educated JWs in your area? Who knows! It's an anomaly for sure.