I can appreciate the argument that players respected each other more in the 70's, but remember - they were all smaller than they are today, they weren't as fast, the puck didn't go as hard, and safety equipment was almost non-existent. Oh, and they didn't get paid a ton, either. In many cases, there was a lot more physical risk with a lot less to gain, so yeah, guys didn't try to kill each other. People losing an eye now and again deterred that.
Players today now wear armor, and use it for more than just protecting themselves. I talked to one NHL player, who at the time was in the AHL and going to his 2nd NHL training camp, and his take was that the physicality starts at the lower levels because that's your shot at the next. Other than the elite talent, everyone else is pretty close, and many see it as always being an injury away from a call-up and a raise from 60-80k to 400k. FWIW, he's now a 3rd liner, which is to say your average forward - exactly the guy who the next prospect is one injury away from replacing.