No. You do not have to pay for parking if just dropping off.
At the Magic Kingdom, stay toward the right (just to the left of the bus lane) at the Magic Kingdom toll plaza. Tell the parking toll taker. Then follow the signs as if you're going to the Polynesian. There's a passenger drop-off and free short-term parking lot for the TTC just beyond it.
For the other three major parks, just tell the parking toll taker what you want to do.