It's called gentle rib poking humor, SBC. I thought it was clever.
For the first time yesterday, I saw those metal straws at Walmart. I blanched at the thought of some child sipping his juicy cup while riding in his safety seat, and Mommy makes a sudden emergency stop, and the environmentally friendly metal straw rams through his gullet. But it is cleanable and reusable. (That's called snarky satire.)
Blind decisions by advocacy groups often have unintended consequences. ESS has some problems too. Extra parts and batteries have to be manufactured for the vehicle at an environmental cost. The engine itself emits an extra puff of exhaust when it restarts, often after a very short down time (I know, I drive a Pacifica). How long before the down time compensates for the restart pollution? I'm pretty sure sure these question are of minor consideration to the manufacturers compared to the sales benefit of 1-2 MPG shown on the Monroney sticker.
As far as a child and a metal straw, that's really taking worrying too far, IMO. The sippy cup alone with no straw could chip a tooth, or cave in a soft skull if thrown. Nothing is 100% safe.
And as far as the ESS system, worrying about the parts manufacturing costs is insignificant, as lead acid batteries are one of the most recyclable items in vehicles, and a beefier starter is better than not.
The fuel savings may only be a small amount, but the less fuel that's burned, the better for the environment, and the better world you leave for that hypothetical kid in the back, even by a small amount.
Finally, ESS doesn't just blindly enable at all stops - As the video linked in this thread shows, the system watches for several conditions to be met first. For example, if climate control could not be sustained by the battery, and the vehicle is not yet warm or cool enough relative to the target temperature, the system won't activate. You don't need to second guess the system, it has reasonable limits pre-programmed into it.