It is difficult to stay definitively whether China should have maintained its commitment to great expeditions. On the one hand, large expeditions bring many benefits to nations. For example, this opens them up to trade, which can bring them economic benefits. Moreover, it allows the trading nations to have access to more goods and technology. Trade also brings new ideas into a country, and contributes to creating relationships of peace with others. If China had continued its great expeditions, it would have had access to all these benefits.
On the other hand, the fact that China became so inward-looking also brought the nation some benefits. It allowed the country to become much more unified in terms of language, culture and politics because few new ideas were coming from abroad. This unification led to a strong defense, a well-functioning burearucratic system and a high standard of living. It also reduced possible threats to the imperial system from abroad.
As China's technology and institutions were much more developed than those from nearby countries, and as their isolation brought them stability, I believe China did not need to continue with its great expeditions, and was instead right in focusing on national matters instead.