Robo-umps would avoid all this irrelevant stuff about pitch framing and offending the umpire.
All that would matter is the objective issue of whether a pitch is a ball or strike. Which is as it should be.
Use of a human ump backed up by replay would just slow things down and require challenges. Why do that when you could get it right every time with no interruptions?
(This assumes that robo-umps are truly accurate or at least far more accurate than human umps and can't be fooled by special tactics).