In my opinion the detrimental effects of a lack of soul juice on the living, namely sickness, weakness etc. is reason enough for Katharsos's soul recycling plant, as dust is needed for life to thrive on Galbar. Removal of soul decay produces a conflict with sides: the selfish old dead, the suffering living and diminished young dead. Burning oneself becomes a selfless act rather than an unfortunate inevitability, Gods can chose sides, have competing solutions to the problem or can simply be apathetic to the entire affair etc. In contrast to this Soul decay as an isolated problem away from the soul crisis only really has two solutions, keep mercy killing or stop soul decay. 

With the amount of detractors soul decay has atm it's likely that we/they will want to take actions to prevent soul decay pretty early on IC anyway if it remains a feature. How and why this is done and by whom could be interesting questions to answer but overall the entire affair is mostly a forgone concision as nobody but demons and death benefit from preventing the cure. I also feel like the answers to the questions are mostly answered by starting parameters as any god who cares about mortals is going to have to face this eventually. The only real thing standing in the way of the cure is the MP hit that the god/group who solve the problem will take and the subsequent burden of guilt for any disasters that result from the cure. I feel that the combined cost and inevitability of solving soul decay would be detrimental to the mustering of motivation to write it in the first place. So it could end up just sitting ignored in a corner with no one wanting to deal with it while the question of "why are none of the gods doing anything about this" and "why aren't mortals asking for something to be done about this" endlessly nag at them. I could be wrong about that ofc, maybe someone is hyped to cure soul decay, hell maybe I'll end up begin that person, or maybe some has a god willing to die on soul decay's hill which will add conflict, but that is my prediction based on my limited rp experience.     

In summary, soul decay's days are likely numbered and the decision that I feel needs to be made is do we want to end it now, or do we want to see it's death play out IC?