Humans have evolved to pay close attention to, and be keenly aware of, their environment. Of course you can't just sit still for two minutes: there may be a snake crawling by. Pay attention or suffer the consequences.
As the Zen enthusiasts already implicitly acknowledged, the ability to concentrate on a single thing may well be valuable, but concentrating on a single thing, especially on a single thing of your own choosing at the time of your choosing, is vastly different from doing nothing, on a moment chosen by someone else, while actually concentrating on something you don't consider interesting.
As the Zen enthusiasts already implicitly acknowledged, the ability to concentrate on a single thing may well be valuable, but concentrating on a single thing, especially on a single thing of your own choosing at the time of your choosing, is vastly different from doing nothing, on a moment chosen by someone else, while actually concentrating on something you don't consider interesting.