I'm well under 40 and I much prefer games without DHs to those with them. Interleague play has allowed me enough time to see the team I really care about play with a DH and I prefer pitchers hit.
I like there being that question of whether you pinch hit for your pitcher in the 5th or let him bat and try to squeeze an extra inning out of him. I like the debate of whether you should pitch to an 8 hole hitter with 2 outs and so get the pitcher first the next inning or whether you should walk the hitter and end the inning by facing the pitcher.
Then there are those awesome moments when you walk a guy to get to the pitcher and the pitcher makes you pay by getting a hit and driving in runs.
I'm not going to say the DH ruins the game, I just prefer having those little aspects over having an extra bat.