One thing I'd love to see in FL is more dangerous environments.
For example, fall rooms have been completely negated by fly and were not that dangerous in any case. I'd like to see fall rooms that are so high fly does not matter. If you fall off the cliff, your dead.
I would also like to see burning rooms and drowning rooms.
In the Volcano there are portal rooms that have scratching pain. However, I think rooms that have you walk on coal and rooms that have transient blasts of lava would be good.
I also think there could be dungeons that are so deep you take drowning damage.
When lightning strikes, it just might strike you.
When its raining, you might slip and storm Giants get bonuses.
Things like that.
This is a call for active as opposed to passive environmental immersion.
Feel free to comment, build upon, or destroy.