The original intent of no pump in park was to reduce drag on the engine when starting. All Chrysler automatics had this feature until around the early '90s. The 604 FWD four speed has always pumped in park. The 470/670 FWD three speed was switched to pumping in park at about the same time and rebuild kits usually have the instructions to drill one hole in the valve body so that earlier ones will pump in park.
I've always checked automatics in neutral unless otherwise instructed. I think I picked this up from Fords in the '50s, but don't remember for sure now. I know I got my first MOPAR in 1969, a '62 Dart 318/727 which had run over 300,000 miles with no repairs when I last saw it.