Nobody is saying that you can't have healthy habits in 2018. Now they have to be a deliberate choice, because the default is driving / riding to work (as most people do). Nor is anyone saying the past was ideal. I am saying we can selectively choose certain aspects of the past as a model for how to make better choices for ourselves in the present. Some other advantages:

- default lifestyle (for economic reasons) is living in the city / suburbs where walking is often aesthetically unpleasant; humans have an aesthetic response to being in nature.

- again for economic reasons, processed food like bread is the default choice; it's hard for some to afford (in time and money) to get all their calories from fresh vegetables and meats. Again the past is a model (I'm talking about humans' natural diet in the days before food preservation / grain agriculture).

- let's shoot for no smog and no cave lung

- social stratification led directly to mass starvation and poverty (poorest segment of society experiences stress-related declines in longevity)

If we assume that every change that's ever happened is for the better in every way, it blinds us as to how to make improvements.