Agree with you Rolf. A-Cats have been leaders in the past. Maybe the status quo of developments means that either cats aren't attracting the out-of-the-box thinkers, or we are on the cusp of the next development but it hasn't been thought yet. The past 5 to 10 yrs has been evolution rather than revolution. But if you look at the A history there have 2 major developments in the past 20 yrs. Taller rig accompanied by carbon mast development, and move to wave-piercing design. But with 9 to 11 different hull designs at recent worlds mean people are still working on one aspect of that. Steve Brewin specifically requested that the Tool he has in Oz had the front beam moved by a foot compared to the standard Tool. Not sure whether that was the case for his Euro's boat, but shows that rig/boat balance is critical and not as an obvious development as something which is being launched out of the water by foils.
Looking at F18/17/16, they are really evolution of ideas rather than pushing anything new. Tornados have pushed the envelope with the adoption of the kite and new jib/main configuration and sail development which has filtered down. But chasing the elusive Olympic medal will do that.