I don't think Nintendo cared about it being handled by kids. This was more likely simply down to fabrication costs.
It begs the question though, why did they even design the dock like they did ? Essentially that entire front panel is superfluous to its design as it's essentially just the USB C dock part at the bottom.
They could have created a far more elegant design that simply had USB C at the bottom and a raised back to support. Slightly angled/tilted so the raised back fully supports.
Something like this belkin dock. Then they could have avoided all contact with the screen and even used the screen in docked mode to display time, battery, controller indicators or game specific screensavers. So much cool possibility opens up, and we wouldn't be left with dread every-time we dock.
It would have also made the dock more portable too for carrying whilst away from home etc.
The dock by comparison to the handheld unit is incredibly poorly designed and ugly for the rather simple/meagre job it has to do ..... It's just a bad design.