I can understand Disney wanting to eliminate off-site guests avoiding the parking fee and taking up parking spots at the resorts. This shouldn't apply to guests of any Disney resorts though. We rent a car, not to go off property, but instead to allow us to dine at the resorts before and after park visits to avoid the delays of Disney Transport. We will park at the Poly, have breakfast at Kona or Ohana, then head to MK for the morning. I'm not escaping a parking fee as I am a DVC resort guest with an AP, and the parking spot typically isn't an issue since it's during the day and never overnight.
If Disney is going to charge me to park there regardless of a reservation/AP/etc, then we will likely stop dining at those resorts. Taking the bus or parking at the parks just makes it too inconvenient and time-consuming. Hope they don't go that route.