Right, if you're having to choose between two models that meet your current needs equally well, and are about the same cost/effort, then asking that question is

Right, if you're having to choose between two models that meet your current needs equally well, and are about the same cost/effort, then asking that question is great. If one of the models is easily extensible to heavier loads, and one is not, absolutely you should pick the extensible one. Or if you're thinking you've got a great design, asking how you'd extend it to heavier loads can validate or challenge that. Those are great considerations and asserting "YAGNI!" here would be a mistake.