Well there's no doubt on the side of the aerospace companies. Anyone can confidently offer to engineer you anything given sufficient time and resources, and a 'plane' that is actually a family of somewhat-related airframes in different configurations seems like a plausible way to be all things to all people given virtually unlimited budget. A certain amount of cynicism is required to bid in such circumstances, but money does tend to distort things.
The commissioning side is much less clear. Who on earth would think one size fits all is the best approach? One possible guess is that it's an attempt to CONTROL complexity and cost, compared to having a succession of over-budget programmes and small orders for aircraft that cost fortunes to develop. A big bet on technology sharing, and an acknowledgment that the development of each new line of military aircraft has already become staggeringly expensive.
The commissioning side is much less clear. Who on earth would think one size fits all is the best approach? One possible guess is that it's an attempt to CONTROL complexity and cost, compared to having a succession of over-budget programmes and small orders for aircraft that cost fortunes to develop. A big bet on technology sharing, and an acknowledgment that the development of each new line of military aircraft has already become staggeringly expensive.