This is kinda nitpicky, but..
I feel like they are too huge!
They are helpful but just the size of them.. they really clutter up the minimap for how big they are compared to the rest of the map!
The minimap style is so subtle, so I was expecting very minimalist symbols, maybe just a small solid coloured block for a key and gate. Even if they were like a 1/4 of the current size, they would still work, and look much better.
Agreed. An elevator symbol doesn't need to be any larger than an actual elevator.