Not all terminals in the States support chip functionality, so for the time being chip & pin cards here still have normal mag strips and can be run as older, regular cards - the mag strips can still be read/stolen & used.
PINs really only just deter someone from physically stealing your card and then using it, so until card theft becomes a problem, I don't think we're going to be moving to chip-and-PIN any time soon.
(On the bright side, Android/Apple Pay are generally good enough to function as chip-and-pin: it's as secure as a chip card, and don't allow thieves to use your cards unless they're either sophisticated enough to get past the fingerprint sensor, or they know your passcode. It's just a bit awkward to set up.)
(though mostly because they don't want credit card payments to be easier than debit or cash).
Funny as it may be my debit card for some reason has a $500 (unmodifiable) limit on chip&pin purchases, but it has no such limit for swipe purchases. When I asked them how is that more secure, I got a verbal shoulder shrug.
Banks are in the business of underwriting. I believe at least on the corporate level they probably don't like the idea of fully secure, verifiable payments, because that would mean you don't need them anymore.
These devices read the data between the chip and the terminal. This would be fine, if payment processing consistently used iCVV/EMV, but it turns out they don't.