I'm coming at this from the view of an Objective C programmer, which was heavily influenced by smalltalk.

Having written Objective C full-time for 5+ years, it is rare to need to use inheritance in classes that actually implement application level logic, however it's used in just about every class you make as you inherit from Apple's base. (UIViewController, UIView, etc..) It's useful to subclass and add categories as needed. At a functional level it's not an issue, however with that in mind I'm not sure it's a great pattern for Javascript.