这是一个语法点：be of + n.,例如：It is of importance = It is important.
句中height(身高)是名词,be （are）动词后不能直接加名词,但有了of就可以加名词（参照上例）,所以,不能省略of.
除非,把are改为have,那就可以去掉of,如：Mike and Tom have the same height.