They're already adding a feature to reset the nether (TU9) for those who generated the nether prior to the addition of fortresses, so why not add a feature that enables players to reset the overworld as well? I'm talking about resetting it so the world is reverted to the same as it was after it was first generated. All the ores reset, all the landscape untouched, no caves explored. This would be helpful in the instance in which you are attempting to play on an old world by copying the seed and generating it again. However, I have found that seeds from former updates (or at least the one I tried) do not work. Or if you really like the world you spawned it, but do not like how it has turned out regarding builds or changes in the landscape, you can simply reset it. I've tweeted 4J Studios about this suggestion but I haven't gotten any replies, so I figured I'd post it here.
But would you really want to loose everything that isnt in your inventory?
I wouldn't and would prefer to just start a new world.
Stay fluffy~