Why might you consider the appearance of overregularization a good thing in the process of a child's language development?

Overregularization is a process of cognitive advance. It signifies that children are actually learning. Many children first say words correctly because they heard someone else say it. They later apply the rules of grammar (overregularizing). Indeed, overregularization is the rules of grammar even when exceptions occur. It makes the language seem more "regular" than it actually is.