Otherwise you're going with a 24-man roster and, what, 13 pitchers? We're back to 19th-century benches. A utility guy, and a backup catcher. Seriously, if you have a 12-inning game or a bad collision between two players you'll have a pitcher playing left field.
We got these relievers just sitting out there in the bullpen not doing anything. Lets have them pinch run or play some late inning defense! Hell why not have last night starter coach a base? Save Wayne Kirby's shirt from his beer belly!