You have no clue what your talking about so let me fill you in...
Early 30s-50s, each studio had a very distinct genre they did. Universal had it's horror/monster films, WB had it's gangster/detective pictures, and MGM had it's romantic-comedies/musicals, then of course there were other studios making various things. However within these genres there was a wealth of depth most of which is what inspired the films you watched today... THEY WERE FAR FROM CARBON COPIES OF EACH OTHER... Three gangster pictures made within 30s were Petrified Forest, Angels with Dirty Faces, and Little Ceasar all put out by WB, all three are RADICALLY different gangster pictures with three very different stories. Same goes for Universal with there monster films. Don't make comments that have no basis