Board Thread:Lore Discussion/@comment-10407900-20140914234758/@comment-4290456-20141013095247

Actually it is a cycle that is much needed. Vaati Vidya speculates that the curse appears whenever an age is extended long than nature allows. This would mean the the Dark Souls "Link the Fire Ending" would be as benefictial as you were taught to believe (at first) but that if you were to link the flame, you were doing nothing but extending the age of fire, and prolonging the Undead Curse (Your personal Soul is lost for nothing). However, this would mean that Dark Souls 2 (which is a confirmed sequel) takes place in the age of dark, explaining why man rules instead of lords. I refer to lords as a species and not a title, but it is most likely the term pigmy human and normal human can be used as pigmy means small. However the term may have been created in order to compare the Lords to the Humans and the Dark Soul.

We know Nesandra wants the throne of... Want, but why? Vaati and some other DkS lore speculators have stated and pointed out that the fight where you fight Nesandra looks like a kiln, however by getting to the throne of want, you can't light it. Meaning that the only way to end the curse is lost to time. Nasandra is also a fragment of Manus, and personally doesn't want the Throne just for power. Because she is a fragment, she has seen what man can do, and she is afraid of man. Vendrick tried to do what he could to hold her back... leaving him to look like a Streaker Gwyn that fallen into depression.

Now because Nassandra is a fragment of dark, she would want to keep the age going, so she may remain powerful as by relighting the First Flame... would lead to die consequences and the possible return of Lords. The means to do so is now gone and the throne of want is nothing more than a human sized chair carved into a slightly larger chair that appears to be able to fit Gwyn's large backside, meaning the original chair was fit for Lords originally. It is also speculation that maybe the throne of want was stolen from the giants, but that seems unlikely as by seeing the general size of the giant (through walkthroughs and this wiki) they all seem to be too big to fit into the room itself, and possibly too heavy for those rock giants to let him pass.

So the curse of the undead could be speculation, but it may be safe to say "hey stop prolonging the current age" just as a just in case scenario.