Mine cupped and I check tire pressure every one - two weeks. I think the Dunlops are just prone to cupping.
I think you're right. The problem got worse when they introduced the Multi-Tread product, and I still believe it has a lot to do with the transition area from the harder center compound to the softer side compound. At the same time, they also changed from a more traditional tread pattern to the current system which can also be a factor. But of course I don't have the test facilities necessary to prove my theory, and the folks who do aren't talking.
Since the H-D recommended inflation pressure is 40 psi, and the maximum I believe on the sidewall is 42, I'm not sure what anyone means by running higher air pressures will cure the cupping. If they're running significantly over the max safe pressure on the sidewall, I'd suggest not trying to convince others to take the same risk they are. Yes, running much higher pressures will reduce flexing of the tire and put more of the load on the center of the tread, and that might have some affect on the cupping. But trading a little less cupping for safety isn't a great idea, especially when you only have one tire holding the rear of the bike (and thus your rear as well) off the ground.
JMHO - Jerry