Agree with the pitchers. Science has almost certainly pushed biology to it's limits, because that's what teams are tying to get out of their pitchers.
Also agree that hitters aren't pushing harder now than they used to; I mean we actually used to have a laughable debate about the merits of sliding headfirst into first base. However, I don't think hitters are more injury prone now than they used to be. I'm sure someone can dig up data that I don't have, but hitters have always been hurt, that's why Cal Ripken's journey was such an incredible event.
Hitters DID use to play through injuries more often, but that was just dumb. Those guys always played way under their normal productivity. The better move would have been to heal them so they can perform to their ceiling later and have a bench player man the spot in meantime. That's pretty standard now, but injured players rarely play well, back then, they simply had too much pride not to play. Plus, teams ran like 10 man pitching staffs, there was way less incentive to put guys on the DL (dated reference) since the bench bats ran about six deep.