The US went chip & signature instead of chip & PIN, so the entire change is basically meaningless.
How so? With chip and PIN, if your card is stolen, the attacker either has to accurately guess the PIN before the chip self destructs (unlikely, but not impossible), or disassemble the chip to extract the data. It buys you a small amount of time to contact your card issuer, and have your card key deactivated. With just chip, your card is stolen, and can be used immediately, so you potentially have a couple additional transactions that you would not have had were it protected with a PIN.
In either case, the card must be stolen. That's the real purpose. A stolen card with a PIN is only going to buy you a few extra hours. The real protection is that the private key stored on the card cannot be non-destructively accessed. It cannot be skimmed without the owner's knowledge. It cannot be stored by a retailer and compromised. The owner is expected to notice the loss of the card and report it to their issuer, deactivating the key.