I honestly don't see a worthwhile argument against turning strike zone judgement over to a computer. You rig up a system to a wristband or something the HP ump wears, Red light = strike, blue light = ball. Ump still gets to make the physical call. It happens right away. It doesn't distract from the pace or administration of the game. all it does is stop dumb, blind old umps from making terrible calls when a better alternative exists.
The zone doesn't need to be perfect, it just needs to be consistent. None of this nonsense of human umps calling pitches right down the middle balls (like with Cimber the other day) or calling obvious pitches a foot outside as strikes. No altering the zone based on a situation or what team is pitching or what batter is up. If the zone is a little off and a ball that's technically a couple inches off the plate gets called a strike that's OK as long as it's called a strike all game long.
Human umps have shown they are crap at making those judgements with consistency. Umpire job security removes the motivation to improve or own mistakes or be held accountable for repeated errors. The system implemented doesn't take umps off the field for play calls that do require a human to make them. And this won't be like doing replay where we have to wait 20-30 seconds after the play to get the computer call. If the broadcast live zone can show strikes/balls (formerly with color coding) in real time, there's no reason this can't be integrated seamlessly in a way that doesn't fundamentally alter the game or its flow.
The only excuses that seem to be left are junk ones like "taking the human element out of the game", which is stupid because you're basically saying you want people to be crap at their job just because at least it's a human. By that logic you can never complain if a restaurant gets your order wrong or if you have to wait 30 minutes for your appointment to begin or the taxi you catch drives you all over the place and doubles the expected price of the trip because oh well, human element.
As a side effect it would also get rid of the whole "pitch framing" thing which, while yes it's a skill that can be cultivated and helpful, is also something that lots of grumpy old school guys like Buck crab about because they don't like the idea of catchers breaking with traditional catcher play for the purpose of attempting to steal strikes. So maybe it would put an end to catchers catching on one knee so much and Buck will be able to stop whinging about it nearly every single game.