Since it was brought up. Touro College is separate by design,because its what halacha wants, not because “that’s what the customers want”.
I heard the following when being menachem the family of R’ Berish Lander Z’l.
In its early years the school was going through a financially difficult period. Someone offered a building to the school on the condition that both the mens and womens division move into the same building (into this donated building, as a cost savings measure). As the Manhattan program offers classes to both men and women at the same time (unlike the flatbush program) this would have meant effectively having a co-ed school and the offer as turned down.