EMV has been trivially broken[1], and it unpopularly pushes the risk of fraud onto the customer. Customers in the US don't want that (especially since EMV is broken!). On top of that, there are a hell of a lot more merchants that would all need to purchase entirely new credit card terminals, which is a much larger undertaking in this country than it would be elsewhere.
[1] http://www.cl.cam.ac.uk/research/security/banking/nopin/oakl...