@ Anon Coward
Until, of course, the retailer gets prompted to telephone the card issuer for a 'spot check', and then they're unable to provide the CVV number.
Admittedly it happens rarely. But it happens.
FYI to various posters above.... Amex are only re-issuing corporate cardholders with chip & pin cards when the current cards expire, and at one point were even refusing to send cardholders a chip & pin card upon request, stating that it is a condition of retailers' merchant agreements to accept mag stripe cards.
Naturally as a cardholder it meant that every time I bought anything it was a complete battle - however a quick call to Amex customer services usually resulted in them straightening out any offending retailers. It did take several calls to get South West Trains to stop their ticket machines unilaterally rejecting the cards outright, however...