When the first lines are drawn again on the border, there will be far less cultural behavior like rape, murder, robbery, pedophilia, terrorism and violence inside the controlled borders.
In addition. The prerequisite for functional schengen area would be the border control on the outer borders of schengen, which exists in legally but not practically.
Most of the rapists, murderers, pedophiles, terrorists and violent people are let in legally, having borders doesn't change much in here. For example in Finland all those things have risen in the last year and the reason is not open borders but refugees who are let in too easily. Arrived by legal ways.