Counterpoint - old (reliable) vacuums weighed a friggin ton. Grandma would call you up to come over and carry the vacuum upstairs so she could clean the top floor. As houses went multi-story, lighter vacuums became the hot item. They were made out of steel, now plastic.

They are even lighter now, because how else are you going to eat a bag of Cheetos when you vacuum. Consumers drive poor quality through buying behaviors, not manufacturers.