This person doesn't seem to realize that the plumber was selling them a bunch of shit they didn't really need because it was a good way for them to make money. The analogue would be an engineer proposing a gold plated submarine instead of doggy paddling across the lake. This plays into the worst fears of the product manager, that you are engaging in resume driven development that benefits you, your sense of fun, and your personal growth, over what is best for the product and the company.