The psychographic segment to which this app might appeal would seem to me to be quite small: are there really that many individuals who are uncertain regarding which marginal expenditure would make them happiest? And it's not clear how a financial institution might "monetize" utilization of this app: it's not an investment product, or a cash management product. So the ROI on an investment in this app would appear to be quite uncertain.
I don't know of any academic research on the issue (or even an analysis of the potentially lost revenue). Can you provide a bit more explanation on your idea? How is it different from an annuity, purchased from an insurance company, using a lump sum distribution from a qualified plan (with possibly an annual cost of living increase)? Such products offer a guaranteed annual payment; although the annual amount may be lower than many would require, given today's interest rates.
The opposition would come from the IRS which, logically, needs to tax money received as income. I'm suggesting that a delay in required distributions is warranted, if the individual is still working. This would facilitate accumulation of savings for a longer life expectancy. Unfortunately this is not a product that a financial institution can introduce, but rather a change in regulations that Congress must initiate.