Been trying to figure this out. I want a superflat world that has regular world depth (aka it goes down more then 4 blocks before bedrock). Top layer is grass blocks, but I keep getting tall grass, lakes, etc. How do I get rid of this?
Also, while lakes and dungeons are decorations they are set separately and they and decorations are not affected by the "generated structures" option, only "building" structures are (villages, temples, mineshafts, strongholds, etc). For example, this is the "Overworld" preset: