I think what you bring up regarding lineup changes for 9th inning is fair. Although most games usually at the late innings change pitchers. Adjustments at the end on the pitching is more likely than not while having the best hitters in the ninth is one way of trying to neutralize the closer. It may make game interesting but it ruins the later innings for pitching.
For what its worth I think the game is pretty balance. When the managers set their lineups they plan based on starting pitching. Whether it goes according to plan will depend on the batters skills and team effort in collaborating hits. While on the pitching side it would be mostly on one player's shoulder to burden if the team's win or lose. Of course the players that field the ball needs to do their job too, but if team has a solid pitching then likelihood of relying on others lessens. 9 batters versus 1 pitcher. Seems a tall order to play against, and to allow batters additional advantage of rearranging their batting orders seems to favor the batters even more.
The is a reason why a closer or a pitcher that comes to the mound at the last inning of a game. It is magical when one witnesses the closing shutout. Have to look at both sides of the ball to make the call. I personally enjoy how the game plays out even though the lineup does not change at the ninth. The closing pitcher of every team has a tall order to make sure no runs score and some have to do many back to back games. Pitching takes a toll more on the body than batting, why give batters more advantage? So to make more hits and runs on purpose? A low scoring game but great pitching is also exciting to watch.
Just my baseball mumbling. What do I know? Thanks.