Not to mention the externalities (air pollution, ground water pollution, ocean pollution, greenhouse gas emissions, etc.).
Or, consider the opportunity costs. What could we be making instead? Perhaps a product that does not have a superior substitute that is already in abundance if not massive surplus (you know, metal silverware).
Or, what would be the net leisure impact of not making disposable plasticware and freeing up all those work hours and resources? I know, you say you don’t work in the disposable utensils industry, so how would there be a net gain for you? And if you did work at a plastic spoon factory, you wouldn’t want the kind of leisure time associated with being laid off. And what about waste reduction — don’t I care about sanitation workers losing their jobs if we dispose of less shit?
And therein lies a key problem with capitalism: instead of socializing the opportunities of decreased consumption, it turns them into liabilities and institutionalizes excess and waste.