Until there's a way to plug a commercial cable directly into the IC to be programmed, there will always be a need for a programmer schematic, since some means for making the interconnection must exist.
all the NXP 'V' chips require is a RS232 connection to a PC. [edit]OK that is not "directly into the IC to be programmed" but still 'normal circuitry'[end edit]

publish a schematic and software that will program any and all of their programmable devices, past, present, a future
that would not be "a schematic" but "many schematics" also, the more sensible manufacturers only release parallel programming info to authorized programmer manufacturers.

Erik