The interest in the US is the European leagues, not the South American ones. Look at all the friendlies that get set up with European football clubs...
I suppose that works both ways too as the European clubs want to increase their popularity in the USA and see if they can cash in, same as how all do a pre-season friendly in Dubai/China etc. In some ways it would be nice to see the USA become a competative league, but on the other hand you're too good at most sports already! At least leave everyone else football