Once I turned 40 my dental hygienists really spent a lot of time educating me on how to properly brush my teeth. It really requires delicate care. (Remember, most of our ancestors didn't live to be old enough to need delicate dental hygiene.)
If something like this works, it'll be wonderful. Carefully cleaning my teeth when I'm half asleep is not fun.
Really low historical life expectancy figures are mostly due to extremely high infant and childhood mortality as well as higher mortality in childbirth. It's not like adults were elderly at 40.
Ultimately an electric is similar to a human but I like that it's consistent. Consistent pressure on my teeth and consistent time in each quadrant as well.
They also didn't consume so much tooth-destroying garbage as we do.