1975 is the first time Topps made their own "Cards that Never Were". Their MVP cards featured 1951 and 1955 Roy Campanella cards and a 1962 Maury Wills card that didn't exist. In fact the 1955 card they made for Campanella not only used black and white photos instead of the color photos (or colorized photos) but he is wearing an LA Dodgers cap. Of course the Dodgers were still in Brooklyn in 1955.
In their 1951 MVP card, Topps also printed the players' names larger and eliminated the rest of the text to make the card more readable. I didn't, but I can see their reasoning. I think if they had done the same thing for Rookies of the Year, they would have been really busy making new cards, especially in the early years.