The PLA already had nearly 30 years to make the shift, starting from the PLL-01 of which was first noted back in the 1990s. And with the downsizing of ground forces, the amount of towed artillery needed would decrease as well. If the PLA had any intention of getting a towed 155mm howitzer, we should have at least seen a couple of examples by now. To be fair this does not preclude the PLA from making the shift later in the future, but suffice to say that it is not on their minds as of now. And I don't see how towed artillery being placed on the back seat means spending more money on them is worthwhile seeing as they will be replaced eventually, then what is China going to do with all those modern shells ? These are even less likely to be fired than general ammunition, especially with the prospect of China getting into a serious land war requiring huge numbers of towed artillery being nill in the forseeable future. And I agree that military decisions are not made on whim, but it does not preclude existing biases and/or omissions and oversight to influence their judgement either. For all we know it is just as likely the newer corps of officers had replaced the old ones without consulting the previous decisions making reasons.