How exactlwy would stopping international travel end "domestic and international commerce"? Are these people traveling back and forth with trunks full of cash and products? I think not. They're travelling to make themselves feel important and because it's a good time, or is supposed to be, anyway.
In this day of electronic communication, web cams, web conferencing and so on, I see no real need for international travel at all. I know I'll get flamed for this, but such is life.
Many loved expats I know return moderately frequently to the USA for family and business reasons.
This is 2006, after all.
We're not all Amish.