Timing Tensioner problems of the 2002 Nissan Altima

The cam chain tensioner in the Nissan motors vq35de and vq40de are prone to failure after the warranty expires resulting in thousands of dollars in repairs. Nissan has revised the parts to prevent the failure from happening but those parts are only installed afterthe failure has occurred. The cost to have this done prior to failure is very high. Surely Nissan should have done something to prevent this from happening before putting these motors into production. . .