It is all about the burden of proof
With magnetic stripes and signatures, banks and retailers had the burden of proof to show that a disputed transaction was not fraud. Otherwise the cardholder did not pay the disputed transaction.
With chip & pin, by default if the pin verification is supposedly completed, the cardholder is on the hook and the burden of proof on possible fraud rests on him. Which is nice, as individuals do not have the resources to fight such disputes.
I don't really care about the technical details of the system - that's bank's business, they want to prevent losses to them, by all means, do whatever you want. However, if said technology is used to shift the burden of proof to the customer, it has to be absolutely 100% bulletproof. Chip & pin demonstrably is not. Just change the assumption back to magnetic stripe/signature mode - burden of proof lies with the bank and/or the merchant to prove that the cardholder made the disputed purchase (more than just "we have these logs that show you inputted the pin") or the cardholder is not liable and the current system is fine.