At the least, the huge focus on lawn in suburbia is ludicrous. But the trend does come from practical roots that are the reason for maintaing low grass in rural areas even when there are no codes being enforced.
Long grass means more parasites and the potential to disturb a dangerous but otherwise peaceful creature.

The reason people in rural areas cut the grass near any used areas is because snakes, ticks, chiggers and various other wildlife relish tall grasses. Tall grass= higher danger. In drier climates, tall grass also increases fire dangers.

By no means am I trying to refute your overall message that suburbia puts way too much time, effort and concern into lawns, it is ludicrous. Especially when those lawns can be purposed in order to reduce your cost of living and the like.
But there are practical reasons not to have tall grass all around your house or whatever.