I think the reason is because it drains the user of their life force meaning it shortens your lifespan every time you use use it. Its only because Nagato is an Uzamaki with strong life force energies can he use the jutsu effectively but yes it has iots drawbacks.
Also I think the amount of chakra to revive someone is proportional to how long they have been dead. Reviving someone like Madara or Yahiko might take ones entire life force because they have been dead for so long.
A weaker version of the jutsu is used every time he repaired damage to one of the 6 paths of Pain
Hmmm, definitely plausible if not obvious. So perhaps if an Uchiha awakens the rinnegan, and I believe they can since the eyes were passed down to the elder son's bloodline, I also believe the activation can be done without any necessity of the younger son's power(I also believe the vice versa, that any adequate descendant of the younger son has the body capable of and can become the jinchuuriki of the Juubi without the need of the rinnegan or any blessed eyes.), then perhaps using the technique just once would require the sacrifice of the Uchiha. Maybe, just maybe, Sasuke will be redeemed and eventually give his life for a dead Naruto.
Originally Posted by artifice
I find it interesting the Kabuto intended to use Nagato to kill Killerbee and Naruto temporarily and then revive them. So killing and reviving people by removing and then returning their souls seems to be something that can be done without too much difficulty. I have to assume that it is more complicated than that when it comes to truly resurrecting someone who has been killed by other means (as Tobi mentioned, he seemed quite irritated that Nagato wasted the power on someone other than himself).
As POW mentioned perhaps it is a case of their being various levels of revival and various levels require a more substantial amount of life force.
Yet I agree with the basic argument that there must be some limitations on Nagato's ability to resurrect people or he more than likely would have just resurrected Yahiko and anyone else that was of importance to him. Having a body might be necessary but I kind of doubt that is the only limiting factor. Tobi has made a lot of criptic remarks about the technique and the very idea of using the technique for himself seems odd. I am guessing that Tobi (who has constantly refered to himself as Madara) was infact refering to bringing Madara back to life. If it were as simple as Kabuto suggested for Killerbee and Naruto to be resurrected though, I have to wonder why he hadn't done it already. We still don't know how Madara was killed, or what Tobi really intends to do, so I am guessing we will learn more about the technique when that information comes into play.
Perhaps what it made it less tricky with Kabuto's situation, is that in his case, Nagato would have the souls in his possession already instead of summoning them from the other world, the pure world or whatever it's called; and also that an Edo Tensei Nagato can resurrect indefinitely without dying.
And witness the sparkle within this world of darkness.