Good question. And my answer is still the same. The umpires are not an impediment, a problem to be solved. They have always been part of the game, the humans who do the essential job of helping to determine the outcomes of games by rendering quick decisions on balls, strikes, out, safe, foul, fair, obstruction or not, HBP or not, balk or not, etc, etc.
I agree with moonslav that the home plate umpires direct view of the strike zone is imperfect, but I would still rather have an imperfect human call balls and strikes than a computer hooked up to cameras.
Computers--and I well aware I am using one right now to type this--have already initiated dramatic change in how the game is played. By determining hitters tendencies, they cause three infielders to routinely be put to the right or left of 2d base. Indeed, those new configurations sometimes prevent infielders from being able to make a double play. Bunts and stolen bases are being computerized away, but swinging for the fences is definitely in.
Meanwhile, games still last longer and longer because dawdling by pitcher and batter remains sacrosanct. Why not use the almighty computer to fix that?