I'm not convinced that your numbers are even remotely realistic for DVC attendance at parks each day. Very far fetched IMHO. You are acting like a DVC employee or something to have such defensive, conservative, high estimates of the impacts of such fast passes. I'm not convincned that they would have such dramatic, acute impacts in the parks, considering not all guests in each villa would actually use all of the FPs, etc etc. We agree that there would be some impact, but not at the high-end of your estimates.
Many days, no the impact would not be so profound. But when you're looking at a situation like this, planners ABSOLUTELY must consider the worst case scenario. It doesn't matter if DVC villas only have registered guests equal to about 50% of their max occupancy on a Tuesday in September. What matters is how the parks would be impacted when the villas are at 90% occupancy on a Monday during Spring Break week.
I did some quick math to determine the max occupancy of all DVC villas at WDW. Among all resorts at WDW there are:
628 Dedicated Studio Villas
885 Dedicated 1B
2417 Dedicated and Lockoff 2B
106 Grand Villas
With max occupancy of 4, 5, 9 and 12 respectively, there could be as many as 24,538 DVC members staying in those villas at any time. So my initial number was actually low.
If I had to guess, I'd say that on a typical day DVC villas are around 75% of max occupancy* and that at least 90% of the guests staying in those villas visit at least one theme park. That's still over 16,500 Fast Passes redeemed in a day.
During peak periods (spring break, Christmas week, New Year's Thanksgiving, 4th of July, Jersey Week, Marathon weekends, special event weekends like ESPN, Star Wars, and any other time of the year when the parks happen to see high attendance) the DVC villas could be at 85% of max occupancy and upward of 95% of those people are visiting the parks. That's nearly 20,000 Fast Passes.
And that's not even addressing the issue of unbalanced distribution of the passes among each of the 4 parks. What if it's a Star Wars Weekend and 10,000 DVC members converge on Hollywood Studios to use their FPs for Toy Story Mania? What if it's the Food and Wine fest and 8000 people head to Epcot to ride Soarin?
Of course these scenarios won't play out every day. But you better believe that Disney will consider all worst case scenarios before they would ever consider offering a benefit like this.
You can claim that a perk like this "wouldn't cost Disney anything", but tell that to the day guest who faces longer Standby times, later FP return times and a more rapid exhaustion of the daily supply of FPs at the premier attractions. When these people grow disgusted with their Disney experiences and start spending their dollars elsewhere, the perk absolutely has a cost associated with it.
[*Rooms will rarely fall below 50% of max because guests would then simply book a smaller villa (i.e. there aren't many people booking a Grand Villa for fewer than 6 occupants or a Two Bedroom for less than 4.) So if we assume that some of the villas will be 50% of max, some will be 100% of max and some will be in between, I think 75% is as good as figure as we will get for an average. ]