It is almost like expecting a child in the womb fly an aircraft just because the parents are pilots and want the child to become one. The soul starts its journey as a seed and develops into its divine adulthood through all the tests and challenges of life. It is somewhat like taking someone from ground zero to the Everest and drop land through a helicopter. The person won’t survive because he is not equipped to deal with it. He may have the will and the faith for reaching but his body cannot take it. So too a direct supramental creation would be just a soul creation and not something substantial. For that the body is needed and hence the long preparation through number of evolutionary challenges.
Affectionately,
Alok Da