You've actually just made a great argument for the DH.
Glavine was a lifetime .186 hitter, and Maddux hit .171 over his career. If this is what counts as "great" among pitchers, then they shouldn't be allowed near a batter's box. Any position player who hits that poorly finds himself a career AAA player -- at best.
Sorry, maybe my memory is tainted by having watched them play as a die-hard Braves fan.