Idea for World Optimization

I've noticed that when you build in a chunk and then remove whatever you built, it still registers that the chunk was loaded and therefore, will forever take up space on your world. This can be particularly annoying on superflat worlds where the end result is exactly the same as the initial world generation, but it still takes up a large amount of space. 

I had an idea where perhaps if a chunk is exactly as it were generated with no differences whatsoever. Then there could be a check that removes the unused chunk from world data. This would be more difficult on a typical overworld map, but it would help maintain reasonable world sizes for superflat builders. It would also better optimize world files by not storing chunks with no data changes in them.