three swings for a quarter

Why doesn't baseball have instant replay?
I understand that for the most part umpires do an excellent job, but there isn't a reason that it can't be done better. I don't want to take anything away from the men who are umps because they do an excellent job but instant replay can certainly improve some aspects of the game. There is no reason for baseball not to take advantage of technology that every other major sport uses.
The only argument I've heard is that it will cause a massive increase in the length of games if Umps were to use instant replay. That's fine in theory but if that's all you got then bring on the review booth. Why can't Major League Baseball have a system similar to the NFL, managers get two challenges per game and that's it and they can't challenge balls and strikes. I don't know the numbers but I would bet that NFL games are not significantly longer than they were before replay. Wouldn't this benefit the game greatly? You don't think that Phil Garner wouldn't have thrown the red hankey last night on that HBP?
And if your really concerned about the length of games keep the batter in the batter's box or shorten the length between innings. OH NO NOT THAT, that would cut into MLB's ad revenue. Baseball has this unhealthy attachment to tradition that surpasses even college football. Change always seems like a death knell to these purists. ( as a side note it amazes me that DH rule ever got passed) Change is good fellas, the replay machine isn't going to steal your souls.