Economic consumption

I have been thinking ( a dangerous place for my mind to be alone) and have decided to start adding little thoughts ( no pun intended) about how as a society ( okay, maybe just as a family unit)we have evolved into needing things ( cars, houses, quantity of items) of a much larger capacity.

My first example. Ford Expedition makes a great SUV capacity of 8. With the average family being 2 parents and 2.75 kids ( still scratching my head with a child who only counts as 75%), why the need for 3 extra seats? Have we decided we don't like being close to each other???, Forbid the time when little Johnny 'creeps' over to little Susie's seat in the car...( I grew up with the 'He's in my seat, he's touching me, he's looking at me' ( Tramp, I am NOT talking about dating at the drive in....then it would've been Carrie's is touching me, she's in my seat...etc HA HA)

Anthropologists will decify us hundreds of years from now and perhaps discover that we needed the extra space because we couldn't handle the conflict resolution of sibling situations that our parents handled while we were unsecured in a car going 70 down the highway with Mom swinging her arm behind her trying to grab one of us!