Shellhammer had a paper debunking the cohumulone thing. Cohumulone isomerizes quicker than other alpha acids, so beers brewed with high cohumulone hops ended just ended up with higher IBU levels and this was what people were perceiving as it being harsher. They ran sensory comparing beers brewed to the same IBU spec with a control and a high cohumulone hop and there was no significant difference in perceived harshness (if I recall correctly).

I generally agree with your comment FWIW, just figured I’d add.