The plane, of course, was designed in the 60s and built in the 70s. I guess design has moved on since then and maybe a more modern machine would not have been so vulnerable to a piece of titanium rupturing a fuel tank. Having said that, there are plenty of old Boeings and Airbuses still flying around that were built at the same time and it could just as easily been one of them that was brought down the same way. If you are going to hold the designers and operators responsible because an elderly design didn't meet modern standards then the thing should have been retired years earlier.