It is no more just that an individual's family benefit from a monopoly over an idea, than the individual who created it. There remains no inherent right to an idea. As for the sale of patents and licenses, firms will waste precious resources in fighting amongst each other for monopoly control over intellectual property, and will even buy the rights to products with no intention of using them, planning simply to prevent any competitors from doing so. The most efficient system is to have ideas be public and accessible and usable by everyone. When they are, more innovation will occur.