Well, we're not sure that they accept this alone. As others have pointed out, we still don't know the precise details of this social engineering.
And the reason that Apple accepts uses just the 4 digits could be because the support rep can only see four digits. Would you be comfortable if the Apple rep could read all your card details on screen? Apple doesn't trust them any more than you should.
From the two attacks we've read about, it seems that a known weak point is domain registration. This is where the fella picked up the victim's full address. Once he had this and the four-digits from the credit card, then he was pretty much home free.
My thinking is all domain registrations should be kept private. I can't see why the registrant's home address has to be exposed for the world to see. That might be a good first step.
Mat Honan and Apple are still being very vague as to the precise nature of this 'social engineering'. Apple says that procedures weren't followed. Fair enough, but if Wired did managed to engineer the same scam twice, then that would mean that Apple's procedures weren't followed...twice. And then the concern becomes how often are the tech supports not following Apple's procedures and why.
Too many questions still.
The big unknown is this 'social engineering' term, because it covers such a multitude of ways in: plausibility, threats, bribery.
Home address for anyone is easily obtainable via a Google search. And the last 4 digits of a CC is not treated as secure info by just about anyone. I see it displayed on conformation email for online purchases all the time. Using either or both of these items to verify identity if foolish at least and dangerous at best.
I know folks may not like it but any sysyem that has money or data (which is just as valuable) involved must take their password reset process to the next level. Making it easy for people to get a reset is nice but puts everyone at risk an unacceptable risk.