No existential truth is absolute. Vonnegut's position of privilege at the time of the writing certainly provided him with a better ability to revel in the finer things life has to offer. Not everyone in this world of ours is lucky enough to have this luxury.
I disagree that modern life is somehow unnatural or participating in it requires some form of submission. Providing for our needs in a more convenient fashion is one of the pillars of civilization.
So according to your logic, a person requires a level of success approximately on par with a Vonnegut to appreciate an errand to the post office? Anyone significantly less successful than him can't consider the possibility of a leisurely stroll?
I understand that not everyone in this world has the luxury of free time, but if one has the ability to shop on Amazon, making time away from work and the internet is almost definitely an option. It's thinking like that which will hurtle us towards an Idiocracy-like reality.
I disagree that modern life is somehow unnatural or participating in it requires some form of submission. Providing for our needs in a more convenient fashion is one of the pillars of civilization.