I have absolutely zero in the way of rational arguments against it--it's just my weird little bit of stick-in-the-mud baseball conservatism. I turn into a hurrumphing grandpa when it comes to ****ing with the idea that your lineup is comprised of nine guys, all of whom have a bat, and all of whom have a glove.
I like double switches. I like the extra layer of strategy when considering leaving a starter in a game for an extra inning even if he has to hit. I like the idea of planning around a soft spot in the order, and the little uptick in tension when dealing with a pitcher who can actually swing a little bit.
I'm not exactly a Luddite. I think Edgar Martinez should be in the Hall of Fame. I just think the game will be diminished a little bit when the DH is universal. But, yes, the game changes. It's changed in more meaningful ways than that over the years. But, having been raised on NL baseball, and always feeling like the American League was somehow second-rate, I'll miss the having the pitcher hit.
But...