Immersion program

Immersion progam is being widely mentioned as a English-only classes is emphasized by a new goverment's roadmap. The new government declare that it starts with increasing hours of English-only classes and to reach at all subjects - that is History, Math, Sience etc.- in English. It became such a hot issue that many people related insists their own ideas about it and I don't agree with the immersion program becuse of following three reasons.
Firstly, being exposed to English in class dosn't readily lead to student's proficienty. English is a language and it needs continuous practice and repetition to be learned. Several hours of English in class is not enough to improve their English. Therefore the contents of English class like texts, reading and listening materials should consist of stuff that students have interests so that they lead to constant excercise.
Secondly, unconditional immersion education only makes a bigger gap among students. As many other people insist, students who can understand all the English teacher said will more improve their language skills, while rest of them do not. Then it can turn out to be either increas of private education costs or lower-quality classes for unable students
Lastly, we should always be aware that a target language should be based on native language.That is, the more we know expression!s and knowledge of mother toungue, the more we get those of a target language. So all classes in Eglish without native language is ineffective.
Hence, I don't agree with the idea that immesion program will be more beneficial for improvement of student's English proficiency.