From what I've read about this rule in international and amateur leagues, the game only slows down when this happens. Apparently, every team bunts the runner over, then the pitcher walks the next guy to set up a double-play and then pitches around him. Between the bunt and the walk you're killing any momentum of the game. That'd be a concern of mine.
If this is true (and it is believable), the obvious answer is to start each half of the extra inning with the bases loaded and no one out. Now wouldn't that be fun? How about let's not get on that slippery slope.
