You do know that the "64 1/2" Mustangs had a 1965 VIN number on them, and were sold by Ford as '65 Mustangs, right?
1965 + 50years = 2015, so Ford didn't mess up the math. Of course, technically the 64 1/2 Mustangs were the ones built prior to August 1964 so Ford is a little late on the building, but on time for the model year.
Also, going back and forth between 2014 Mustang front photos and 2015 Mustang front photos and the grill isn't even a whole lot different, but the overall look is. To each is one, but far from ruined.
Then why did Ford tag the '09's as the 45th anniversary edition?