I wouldn't mind better lever rewards. Right now I hardly ever pull them as the risks outweigh the rewards, especially when the outcome is uncertain.
Pre-N!, in the past, after clearing a level out, I would find levers 1 space away from the walls (or door) of a room, use a barrel to remove the wall but not the lever (unnecessary if door is adjacent), then pull the lever - if it flooded the area with lava/acid, move away, no problem. (Also move barrels away, in case of a 'barrel explode' lever too.) Since enemies have been cleared out, the very dangerous "erases walls" lever is not so dangerous.
However, the benefits aren't worth the risk, unless you're desperate for healing. And the 'damage enemies in same room' lever is rarely useful - if there was a few enemies in the room that weren't dangerous, there's not much benefit, yet if there's dangerous enemies in the same room, chances are you've already a smoldering blob before you can even take advantage of the lever.
If you've developed a sufficiently high damage per second output, then the 'spawn enemies' lever can also be beneficial for extra xp, but it can backfire.