I have noticed a definite decline in quality on my new (3 year old) passport vs the previous one. The previous one survived a decade of travel without the gold "leaf" rubbing off at all. In a single trip only a few months after I got the newer one, it had begun to rub off. I don't think I treated it any differently, either - it's not as if I went hiking in the jungle!

However, the worst part about the newer passports is that the personal information was moved from the inside of the robust back page to the flimsy penultimate page. It's noticeably more fiddly and time-consuming to present this to security or immigration officials, and I suspect is easier to damage the new ones by scrabbling around for the right page.