In the 1971 Topps Baseball set Topps issues game in-action photo of players on their regular card. Also (much to my dismay), Topps issues vertical photos of regular player cards in a primarly horizontal card set. Previously, Topps issued action cards on subset (like the World Series subsets). It should be noted the 1956 Topps set, a completely horizontal photo card set, had painted action photos in the background.
Thurman Munson card (his 2nd year card) is worth more than his rookie because it was card number 8 in the set which made it the first horizontal in-action regular issued player card ever. The in-action photos would begin to pop up in 1972 Topps football, 1972-73 Topps Basketball and Hockey.
In game action photos on player cards have been the standard ever since.