Because by paying $12 I get to enjoy the park with under 3,000 people in it (that's all they sold) rather than who knows how many thousands that do it now that it is free.
Last year there were times when I could turn in a complete circle and not see another sole in MK and I never waited in line more than zero (0) minutes because there were no lines. You just walked up to the ride and got on. Very magical. I prefer e-nights and wish they would bring them back.