Simple. They will not take it into production (to market) unless it offers advantages over the current method. Apple doesn't aim for "specs" they aim for "results". Of course it will also support profit margins.
Not hard for customer to justify paying a premium on a product that has a scratch proof screen (Sapphire can only be scratched by Diamond the next hardest substance) and it highly crack resistant. Remember, this is synthetic Sapphire probably bonded to the LCD.
Ok, facts help too...
May Be Made of Sapphire
"Manufactured sapphire is incredibly strong and scratch resistant. Now falling costs and technology improvements could make it competitive with glass....Sapphire is harder than any other natural material except diamond; by some measures, it’s three times stronger than Gorilla Glass, and it is also about three times more scratch resistant."
By those standard keys in your pocket will not scratch it and common drops won't shatter it. So after that it comes down to abuse and negligence by the users - not Apple fault or responsibility... customer satisfaction soars into 99% from 80%.