Whilst i understand your point, each desynth class has its own specialist item. Just look at ltw desynth and what its done to fieldcraft prices, it's your choice at the end of the day on what you level.
Culinarians get special items only available to them, alchemy can only get certain items etc etc
i strongly suspect that the new trade in artisan items will become desynthable but in doing so they will need to cap these at 1 master d