Today's boats are much shorter and so all the wear goes into the same places time and time again. In a Dancer, the wear was all bow and along the wall ... 11 feet of it! Today's boats have only 6-8 feet for the same weight paddler and are expected to take a lot more abuse. Sure Dancer's and Crossfires ran just about every creek / river out there, but rarely did many of the rocky boofs, low-water slides, rock 360's or seal launches that are common today. I think spreading the load over a longer area had a lot to do with their longevity as well.
Prijon's a more dense plastic, due to the blow-molding process, for their weight, but end up with parting line / edge problems since there is less plastic at these flex spots. These hulls will last a LONG time and the roundest ones seem the best bets.
So while it may help in some cases, I'm not sure we should encourage companies to throw in MORE plastic and weight just yet. Wear - sure if there is more plastic there is more plastic to wear through. But impact cracks - cooking has a whole lot to do with it. Many of those light Riot boats, as well as the Steamboat-cooked Wave Sports boats, are still on the water and despite years of hard use.