We pay for the parking under the hotel. We like our car under a roof, also we buy a lot at Gen Con and hauling that to and from offsite lots is not worth the cost savings for us, but as they say YMMV.
Well, you listed it as a "con", so I was providing an alternative. If you have a connected room, why store stuff in your car?
We do not store stuff in our car, but taking it all to the car at the end of the con is already an ordeal. We literally pack the truck full of a midsize sedan. Pretty sure we had 2 oversized bags of games and at least another 5-10 CSI sized bags. We buy a lot.
I think its good you put an alternative out there for people.