Many manufacturers may be reluctant to include this feature, especially on less robust models, fearing damage to the scope's internal assemblies caused by the extra leverage. This would, in turn, create more warranty claims, unless the scope was redesigned for increased durability, which would drive the cost up. However, I agree that the top tier models should give you the option, and given time they probably will. This is not a new idea. I have seen several scope models from the sixties and seventies that included this feature.