Heavier denim is certainly overhyped in terms of durability. Sure, it would protect you more than 11oz jeans in a motorcycle crash, but thats not necessary for most people.
IIRC the reason Iron Heart (before its British dealer seemed to take over design and operations) developed its original heavy denim was as an alternative to leather pants for riding. This is also I think part of why their heavy denims tend to wear soft rather than stiff.