I don't know, is this even possible? But supposed it is, there might be advantages if old and inactive coins are reintroduced to the network, but I think the disadvantages far outweigh them. There are definitely technical matters that will be introduced that will surely compromise some fundamental rules of Bitcoin. I am not technically knowledgeable to get into it in details but I wonder who will be powerful enough to be able to bring back lost coins? Will it not damage Bitcoin's decentralized design?