Hi Linbin,
I am agreeing with your points. Dorsiflexion is, in my opinion, the most important movement that your ankle can make.
Alot of people can not perform a simple modified squat where they cant squat down to their ankles with their knees over their toes. If the muscles in the deep compartment are "tight" and inhibit appropriate dorsiflexion then minor strains are common which causes inflammation and swelling and compresses the structures within the compartment. Just a symptomatic treatment wont work as the joint will be prone to poor range of motion. Re-education is the key to reverse the cause of the symptoms.
Hope this helps
Adamo