I will ask one question :
Does the workplace and companies not have coworkers who are both male and female ?
Does the colony , society you live in doesnt have both males and females ?
Does the family not have both males and females ?
Then why isolate males and females at a very formative age of school and college when they have to interact with each other throughout the rest of their lives.
Co-education is important because it not only enhances the interaction between opposite sexes, it helps get rid of one's innnane inhibitions and be more fluent in your activities later on when you have to work in office and survive in society in general.