The decline of manufacturing

From today's Washington Post:

A six-cylinder engine rolls down the conveyer belt and stops in front of Bo Huenke every 28 seconds. He attaches a metal pipe, twists in four screws with hands that suffer from carpal tunnel syndrome and finishes just in time to stretch his back before the next engine arrives. His hands move from memory while his mind calculates the math: 28 seconds per engine, eight hours each shift, five days a week, 13 years until retirement.

...When Honda called a decade ago to offer a $23-an-hour job, he hardly hesitated. Lima had lost 8,000 jobs in the previous 25 years; no decent-paying work was beneath him. "Yes," he said. "Thank you. I'll take it."That decision has resulted in two hand surgeries and constant shoulder pain. "It's like getting beat up at football practice for eight hours," Huenke said, "but you do anything here for steady money."

It's true, manufacturing work tends to involve physical labor, which becomes more difficult the older you get. It's also hardly the most intellectually stimulating employment. So why are people concerned about the number of Americans employed in the manufacturing sector declining?