The whole public school system needs to be overhauled. But based on what I have seen, this is very unlikely to occur, given that it is a system beset by bureaucratic inefficiencies, where promotion is based on seniority, above all else.
Perhaps Thai people should take a cue from their brethren in Northeast Asia. The Koreans and Japanese have the same problems as here in their public school system, where the majority of English teachers are competent in grammar, but can barely speak the language. To rectify the problem, the above send their children to private English institutes, where the focus is on speaking. The results seem to bear some fruit.
Thurston Karvy