We are seeing a lot more aluminum used than in the past. But we still see cast iron on the "heavier duty" machines. Aluminum is much cheaper and easier to manufacture a finished part with, but cast iron is much stronger and really has no downside except for the expense and weight. Weight is an advantage on the front of the machine so it comes down to cost.
And as we all (unfortunately) know, a great majority of today's machines are not built to last forever
they are built to maximize profits. I'm not saying profits are bad - we wouldn't have any companies making anything without them - but I am not a fan of maximizing profit by reducing quality.
What you are saying is true to an extend. However, there's is the other side of the coin that I'll just throw in for consideration.
With the aid of computers, CAD systems, and Finite Element Analysis, many companies have utilize these tools to optimize the design for the specific duty and stress. Gear cases can be made lighter and of different material that is suitable for homeowner use. It's smarter use of material, reduce costs to manufacturer, reduce unnecessary use of materials and energy, and makes it more price competitive. Sure as a layman, we may naturally want things heavy and thick as it can represent robustness and reliable. I can tell you these costs reductions are not merely driven by profit, but to remain price competitive to survive. The age of computer and global economy has made that practice a necessity. Consumers drive down costs, squeezing profit margins from suppliers. It's a vicious cycle.
As a consumers, one must realize that these changes are our own doing too. Make your purchases wisely, and think about how it does affect the future the next time you step into Walmart, Costco, Home Depot, and Sams Club.
Americans wants things cheap, high salaries and wages, with good benefits. Ask yourself how is this expectation sustainable. For every American citizen, there are 20 other people who will gladly produce what you want for a whole lot less pay than what we expect.
