We have a family of 6 (2 real adults, 2 disney adults (ages 12 and 14) and 2 kids). As
DVC members, our biggest cost are the tickets. If there was a program where we could pay monthly, I know we would buy APs and travel to DW more frequently.
Again, there is such a system. Set-up a separate vacation fund bank account and start the deductions today.
Currently, we have been going every other year. I'm sure we are not alone. I think anything that would bring visitors to DW more frequently would be something that Disney would want to consider. Add in that they already have an existing program and existing computer system to handle this and it should be a "no brainer".
The biggest problem is defaults.
The current system isn't a savings account, it's essentially a loan or promise to pay. Disney accepts a modest down-payment and then collects the balance of the AP cost over the next 12 months.
That's all well and good for locals who would be inclined to visit the parks repeatedly.
But for people living 1000 miles away, it could quickly morph into the latest and greatest way to beat the system. Instead of paying $2-3K for tickets for that "once in a lifetime" trip, just give Disney a $500 downpayment and close your checking account the day you return from vacation.
I suspect the rate of defaults among non-residents would be much higher than residents. It forces Disney to actively engage in collections against those who do not pay.
There is also a baseline cost to administer the program (which would grow if offered to more) and Disney loses interest revenue from those who would otherwise pay in one lump sum.
Payment plans are relatively new to Disney--particularly at WDW--so perhaps they will expand it over time. But it will certainly be more costly to administer if offered to the residents of 48-50 states rather than just portions of 2.
In the meantime, I still say the best alternative is to create one's own payment plan and earn interest on that money in the process.