It is a sensitive topic, actually. Specially in the United States and Europe.
On one hand, there should be clear and strong immigration laws and legal path for those who seek to move into a new country in the correct way, on the other hand those who are desperate enough to risk their life and freedom also are supposed to be considered, they are human beings after all.
A Border is not only about drug smuggling or illegal activity, there are also cultural and human barriers which should not let us forget we all bleed and suffer the same way as human beings.
I agree with you the problem is not in the border being opened or closed, the problem is what are the laws and regulations that have been put in place to regulate the activities and check both entry and exit of a country's border to checkmate if everything follows governments policy and laws, border mean a lot to a country since that is the door to the country it must be safe guided if not a country can lose their freedom through
Unchecked access in some borders, like in my country where the land border has been freely accessed by foreigners from other close countries and thahas affecteded the security situations here as the is a high rate of arms smuggling for illegal use.