Probably because prior to the chinese/asian global market takeover stuff used to feel heavier, studier and everything was overall better made. Nowadays everything is manufactured in Asia or China. The industry changed from metals and alloys to plastics, or different lighter/thinner types of plastics (chemically speaking) to reduce manufacturing costs. Not only that but because cheaper and lighter materials got developed in the last couple of decades. Nowadays heavier stuff normally gets associated with good quality, maybe even vintage depending on what specific object/appliance you're talking about. For example I've got a metal fan that's incredibly reliable and works like a charm even though it is 60 years old. On the other hand, I guarantee you that a chinese plastic fan won't last 15 years. Heavy and sturdy things tend to hold pretty well to the everyday use, plastic stuff breaks and bends too easily, they don't handle pressure very well and will eventually fall apart.