The "No Generated Structures" option will still generate Dungeons, as well as Nether Fortresses in versions 1.0-1.7.10. However, some see this as being against the spirit of No Generated Structures, namely categories not being reliant on chest loot.

For example, this "Enter Nether" run sets Generate Structures to OFF, but is still able to use loot from an exposed dungeon:

Thus, we have decided to host a poll to decide whether we should allow accessing Dungeons and Nether Fortresses in the "No Generated Structures" category: https://www.strawpoll.me/18521937

The ruling has been decided long ago, but just for clarification, accessing Dungeons and Nether Fortresses in the "No Generated Structures" category is not allowed.