**Standards are not a reason to design in secure systems.**

While Apple has no control over the standard, they do have control over their systems.  Apple already gives security alerts when SSL-CERTS do not match the domain used.  There's no reason why Apple could not give an alert if the display and response number for a SMS differ.  

Further, their response that iMessage fixs this issue appears to show able knew of the issue, but decided not to design a solution for it without breaking the SMS standards.