I think you'll find that there are groups of people who very strongly believe that their "80" should not be reduced for someone in another country to join the USA.<p>In fact, you'll find that there are groups of people who wish to expel certain groups already within the USA in an effort to try to raise the average "80" up to "85", thinking that removing some people will benefit everybody else.<p>Furthermore, the groups of people who think this way are organized, vehement, and militant.  So this type of "just let them all come over here" attitude can become quite hotly contested very quickly.