Hard to argue the 737 NG is not 'safe' given it's track record
This was exactly the argument used for the Nimrod MR2 until 14 aircrew were killed by a latent airworthiness problem that had not manifested to the point where it had been recognised in the previous 25 years. (Yes, the number of aircraft and hours flown were a couple of orders of magnitude different but it's the same logic.) As ever, it's the combination of unforeseen circumstances that are the killer but if the manufacturer had foreseen and ignored, you have a very different equation.