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answer to the question. Summary:
If customers want a secure platform, they use iMessage. If compatibility is the concern, they use SMS. SMS is not, and has never been designed to be a secure platform.
Telnet is an unsecured communications medium. How many computers pop up a notification that says, "Are you sure you want to use telnet, it sends passwords in cleartext?" Is Apple liable because OS X doesn't have a popup that notifies someone trying to use telnet that it isn't secure?
My turn to ask a question. Why are we bent on finding excuses to make Apple fix this, instead of having the cause of the problem (the SMS standard) fixed? Why is fixing the symptom logical when you can cure it at the cause (the carriers)?