"No need to waste time" evokes efficiency, not the national pastime.
To remind. No one on the playing field can see that rectangle which we ,watching from far away, now take so much for granted. My goodness does it feed our little egos to know something nobody on the field of play knows. We alone are always right when no one else is.
Sports and especially baseball are all about striving to make the right play, to hit a round ball with a round bat squarely, to throw strikes that are not easy to hit, to make the right throw or catch, to gain an advantage on the basepaths--and yes, to make the right call on the field. They are not about perfection.
So, me, I can live with robo umps only if the hitter, catcher, or pitcher immediately challenges a call. If the hitter challenges a strike and is wrong, he should be penalized. Same goes for a pitcher or catcher challenging a ball.