Let me try to understand you. Basically, what you're saying is that everyone in today's world is doing it wrong, and that's why nobody receives their arms or legs back, correct? And that the people back in biblical times were 'doing it right', and that's why they were able to heal. Am I close here? Correct me if I'm wrong.
Let me propose a second possible solution for you. Before I write it, however, I'd like to ask you to make a detailed breakdown of where my upcoming logical position fails in terms of what we see around us. Can you do that for me please? Alright... Here it is. What if there was no God to heal amputees? If that were true, would that satisfactorily explain why we don't see amputees grow arms and legs back? Forget that you believe in God and approach it from a neutral position. If it were true, and the entire universe were a naturally occurring phenomenon with no supernatural intervention, would that explain why amputees are getting arms and legs back? It's a simple yes or no question.
Now, you might try to argue that my explanation does not take into account the biblical accounts of healings like Jesus and Peter that you mentioned. Rightfully so. In and of itself, it doesn't. But now, here is another possible explanation for that, that is fully congruent with the notion that God does not exist. Here it is... the healings never took place, and the bible is a religious work of fiction where people lied about miraculous healings. So if God is not real, and the bible is a work of fiction, would that not satisfactorily explain why we have no miraculous amputee healings today, and why we have writings in the bible that say healings happened 2000 years ago? Try to back out of your God belief for just a moment and see if you can make sense of that. All you really need to embrace is the notion that people can lie. Can people lie?
Your solution, while theologically sound to you, proposes an entity for which we have no evidence, and assumes that people 2000 years ago were capable of suspending the very laws of nature to provide miraculous healings because they were able to do the right incantations, movements, gyrations, potions, herbs, wording or what-have-you. My solution does not propose an entity that we have no evidence for, embraces the reality that we see around us, and the only assumption we have to make is that people sometimes lie. Do you really think yours makes more sense?