It is surprising when you see how limited some pros are with their "wrong foot", I'm sure I read in Steve Peyyman's first book that when he was a kid Spurs spent one day a week with players practicing with the weaker foot. Looking at old footage of Spurs in 60/70's teams most players appeared to be competent with both feet, I know it was a slower game and "the press" wasn't a tactic back then.
I've followed our youth football for many years and notice that virtually all the players are good on both feet but struggle when stepping up when playing against mens teams, it's probably down to pace, organisation and physicality of opponents and the obsession with possession in the game. At development level they are encouraged to be positive rather than play it safe.