They found out in 1990 that JWs don't send much money if they are not obligated to do so when the cover price for the literature was dropped.
Even before that, when food at conventions became on donation, wt changed to "simplification" because -no money. Now, cheaplikeones had to bring their own food from home, or go to an expensive fast food instead of just giving a reasonable donation for the food.
They are repeating the same mistake when they think JWs will send higher donations for KHs with no contractual obligation to do so and with nothing tangible in return.
Not a mistake, WT doesn't think in terms of cause and effect; they trust in God. (It appears that) JW as individuals have not realized their financial obligation to support wt and pay their personal share of expenses for the KH, the cost of producing spiritual food and financially supporting the preaching. Sadly, in total dollars and cents, at the end of the month, jw are not impelled to do so. But gradually or otherwise, JW will feel the inconvenience or expensive burdens resulting from cutbacks; and or hopefully (even as you have stated) and as Sparky has keenly shown ( Nice!) is the new source of income for WT funding, everyone will feel that they want to contribute more dollars.