Answer:
Well, it's an ethics question really. There are no real physical disadvantages. (Unless you engineer everyone to be the same, then we can't evolve and become dependant on cloning and genetic engineering to be able to breed and stay one step ahead of viruses)
There are alot of disadvantages...like people can make clones without heads so they couldn't breathe, people can make them smater, more athletic, and sexier than normal people. Everyone will soon be the same and there will be no job oppertunites because anyone will be just like everyone else. Some scientists even think that the clones will age quicker too. Plus Genetic Engineering is against God's will, it's unnantural, and it crosses the species barrier.