The golden key frequently found on various levels and often required to advance past a gate feel... very contrived.
It doesn't really add to a fun factor or grant any sense of accomplishment. Or increase difficulty.
I understand the intent and recall the days of playing Link to the Past, however the golden keys in -those- dungeons actually came as milestones. Perhaps a similar application could be used here. Perhaps the golden key might come as the result of a mini-boss? It isn't required to reach the end of the dungeon, but might turn into a section of notable chests (not the typical off-branch 5-chest dead-end)?
I really like the way the keys are used in levels like Cravat Hall; there are two keys, and two doors. One leads to treasure, the other to the exit. The keys are protected by a gaggle of monsters.
So, the players have a choice: use the first key on the exit, or fight through twice as many monsters to get the treasure too.
I'd like to see more areas like this.