I recently flew with a TK guy who explained that the shear quantity of M&Gs that have already been distributed effectively devalued them to the equivalent of a job fair attendance, assuming the original intent was to score them higher in the first place.
They should still be pursued by applicants, but they're not a magic bullet and should be included in your well-diversified application "portfolio" alongside job fairs and gobs of flight time. Being a son/daughter and/or former intern is a big bonus.
Don't shoot the messenger...