I think making them non-respawning except for boss rooms would at least be a step in the right direction. At the level I'm at, at least, destroying one with fire touch takes a pretty huge time investment. Often I don't see the point to doing it in the first place, but I like the option in case future changes necessitate it.
On a totally different tangent, if the point of monsters is to make it more interesting to traverse areas without just feeling like you're running through the big empty, perhaps another option would be to have many fewer but much stronger monsters, rather than the rather minor annoyances that they are currently. That way instead of there being a bunch of trash that you constantly jump over, you instead simply have the constant threat of a big bad coming down and smashing you, which builds interesting tension even if you never actually see it.
That just gave me another interesting idea. You could have a building with nothing in it except a boss that follows this logic and stalks you from room to room. Maybe he's the only thing in the whole building. Maybe the point is to find his spawner and destroy it, which then makes him vulnerable to attack. And then once you kill him you can get access to his cache of items secreted away in the building. Maybe add sound effects when he's nearby, and if he sees you he chases you for a few rooms until you give him the slip. Of course that would require adding in the ability for monsters to chase you across room transitions, which I know I've seen suggested elsewhere already. But that's a way that you could make empty room travel interesting without needing to have lots of little baddies around to get in the way.
Any way, as usual I'm wandering off on flights of fancy in answer to a simple question. No respawning spawners, good idea.
