Understanding dihybrid crosses is important primarily to grasp the complexity of inheritance. Dihybrid crosses involve two traits that are inherited independently, as described by Mendel's Law of Independent Assortment. By studying these crosses, one can gain insight into how multiple genes interact and how traits can be passed on through generations. This foundational knowledge is crucial for studying genetics, breeding, and understanding the inheritance patterns of various traits, including those related to genetic diseases and agricultural practices.
While the other options you've listed (predicting environmental changes, understanding genetic diseases, and creating genetically modified organisms) may also relate to genetics, they are not the primary importance of dihybrid crosses specifically.