Here is food for thought. Amputees are not healed because no one in these times believes it can be done. There are stories in the Catholic church of amputees being healed but even I see it as a possible legend. So for example since Jesus could not heal many in his hometown because they didn't believe he could do it, so he couldn't. That is in the bible. Plus he often said to people, "your faith has healed you".
Thus I repeat since we humans have a hard time believing God can cause an arm or leg to reappear on someone who has lost their arm or leg Jesus, who is also God, cannot heal us. It is a requirement that someone has the faith that God can and will do it and those people are almost non-existent. I have added another requirement unintentionally but it is also food for thought. What if we believe He can but do not believe he will. The book of James speaks of this saying if we are double minded we will get no healing. So some people know God can replace an extremity but have a hard time believing he will.
So my answer is: lack of Faith and lack of Trust.
peace and good health to you,
So wait, god is dependent upon human faith to give him powers? So when humans express faith, he absorbs the "faith energy" like a sponge and uses it to empower himself? I guess that would
explain why he's hung up on the whole concept of "faith". However, that would also mean he can no longer be considered an omnimax being (or omni-anything), since his powers are limited and controlled by lesser beings. It also raise the question of how he was able to form the universe in the first place, considering that no "faith energy" would've been present at that point.