I don't know the "why", but I do know last year they charged an annual membership fee (10 or 15; I do not remember) + a $25 daily ride fee. This year they went with the "no annual membership" model + $30 daily ride fee.
I do not know if they are offering more either.
Feel free to shoot at the messenger! I have nothing to do with them really; I just like the place and they seem to have almost no footprint on here.