Though, that argument implies that the only plan god has is death for deformed children. If everything is or could be part of god's plan, then you could be as useful as Hitler or everyone else by simply being you and doing nothing.

The more fundamental question to answer is "how would you completely stop suffering?", which I find impossible without taking away everyone's free will.

What if eradicating suffering means that everyone has to go through equal amount of pain and hardship? Would that stop everyone from complaining or would it make everyone complain? What if preventing a greater suffering requires a lesser, necessary suffering? Would that stop people from complaining about it? What if everyone has to take the consequence of one man's fault in order not to make him suffer?

I think the only way suffering would truly stop is if everyone shared the same goal and had no ability for independent thought.