The longer a feature is implemented, but not being used in real scenarios, the more the context for the feature is lost. By the time it's in customers hands, the original reason for the feature may be lost in the smoky mists of memory. And as feedback on the feature comes in, it takes time for the team to re-acquaint itself with the code and the reasons the code was written the way it was. All of that ramp up time is wasteful.