Yes, IQ does matter. Now think of this in relation to the Islamic world, where marrying your 1st cousin is an accepted practice, which brings along with it a whole host of genetic issues as well as lowered IQ.
The link goes to an article on why IQ matters to an economy. Read it all. And then ask yourself why bringing in millions of people from lower IQ nations, who are relatively uneducated and unable to assimilate into our culture, is a good thing.