Same here, September reservations at the BW, taking our second large out of state trip on a platinum AP. To be blunt if I am travelling 1,000 miles, have purchased a Platinum AP, and am staying in a Deluxe on site property I expect park access every day and no hassles about it. A block of reservations should be included with the villa booking. This is a minimal expectation given what I have been charged and the already reduced park experience. Maybe Disney needs to think like an airline. When airlines overbook or cancel a flight they can re-book you a seat on a competitor with a similar flight schedule. If Disney can't provide entrance while I am there they should get me a ticket and free Minnie van transportation for Universal. It needs to be a ticket for both Universal parks as I had a park hopper AP. Maybe they could kick in a Seaworld option as well!
Airlines typically only rebook you on other airlines if the issue is their fault (not counting overbooking) like if the plane they scheduled you to fly on breaks down or something, and they rarely do it when there are weather issues unless you are a top-tier frequent flier (and even then not often).
That said, I really don't think most people on DISBoards are going to have to worry much about park reservations. They aren't going to be like an Ohana ADR or FOP/SDD FP that disappear immediately. Conservatively, we are talking 10-30k people in each park, unlike something like Ohana which has the capacity for 500-750 people per night. So long as you book park reservations when you are able to book them you should be fine (and based on the info we have since you have a resort reservation and an AP you should be within any priority window they create). The only park I could see issues with is MK and even then, it probably won't run out within the priority window just maybe sometime within the general reservation window (depending on whether things like SWGE will be opening with DHS and whatnot).
Disney has to establish that a resort reservation doesn't guarantee park entry because it literally does not do that. Under the new rules, those with resort reservations are still going to have to make a park reservation as well. With whatever priority system Disney comes up with it should be fine for those who take advantage of the priority window or even just reserve their parks reasonably in advance. The caveat that a resort reservation doesn't guarantee park entry is mostly targeted at the resort guests that will show up at their resort with no park reservations and then get mad when they can't go to the parks. It's shocking to me how many people I know who have made resort reservations and bought tickets well within the previous ADR and FP+ windows and then don't take advantage of them and come back cranky about lines and how hard it was to eat anywhere. Disney knows that there will be people with resort who don't make park reservations and show up expecting to get in, so they have to make it clear that that is not the case.