What is up with speaking Turkish through the lessons?

Okay, we were just discussing this today with one of our teachers, whether or not teachers should use Turkish during the lessons. In my point of view since we are all going to be English language teachers, we should all get costumed to the language as much as possible, therefore teachers should speak English and English only and they should not respond to the students who speak Turkish during the lessons, that way we can at least feel like we have an international environment. The students should also be capable of answering any questions that the teacher poses, so that the lessons can go smoothly. Unfortunately this is not the case in our department, actually I thought that the reason for our tuition money to get a %65 raise this year, was so that the education can be %100 English. Lets put a side the fact that the teacher are supposed to speak English and the fact that only 2 or 3 of them actually do speak English during classes. Taking phonetic, the study of the sounds of human speech, tests verbally would be enough for now.