Watching another one of those Golf Channel programs highlighting a match from the 1960s (including the one on now!), I'm struck by the differences in putting styles between players of that generation and current ones.
Lots of golfers back then -- Casper, Palmer, Frank Beard, others -- had a putting style/set-up in which the hands were kept very close to the body, arms moved very little, and the stroke action was mostly with the wrists. Compare to, say, Mickelson and Zach Johnson (two very good modern putters), who extend their arms from the body, and seem to have very little wrist action in their putting strokes.
The long way to the question is this: Have putting strokes simply evolved, the way placekicking has evolved in football (straight-on to soccer-style), or was that kind of putting stroke used by Casper et. al. a response to green conditions (slower, most would concede), grass types (bermuda?), and overall maintenance practices?
Billy Casper is generally acknowledged as one of the best putters the game ever saw. Why don't more players copy his style?