Delta Faucet's plastic scrutinized

Two years ago, I was warned by a friend that if I went with a Delta faucet, it would fall apart. I did not heed that advice because I liked Delta pull-out faucet model 474 NN (NN designates brushed nickel). Indeed, two years later, threads in the soft plastic that holds the aerator in the spout stripped. To its credit, Delta customer service shipped a new spout free of charge the day after I filled out a simple e-mail form describing the
problem. In checking on the order , a cheery and competent customer service rep came on the line and confirmed the shipment. I was impressed.

But it made me wonder what type of plastic was used in the spout. What were engineering and cost tradeoffs made in deciding what plastic to use? I'm mechancial enough to screw in an aerator without mauling the threads, but I thought this plastic was unusually soft. After all, anyone is going to clean the aerator from time to time and that means removing it. So I my call is into Delta. Stay tuned for explanation or offer your if you have one.