I mean, if I'm only going to take 20 fire damage for walking through a massive field of fire...why would I waste my mage's turn on putting it out?
Because moving may mean the two opponents next to you get attacks of opportunity, and perhaps you would prefer to remain where you are and hit them instead?
I think this would drastically change how the combat in D:OS works, and not for the better. It would shift closer to "traditional" RPG combat, where the fighter runs in, healer heals him, and mage sits back...with nothing really exciting. Not what I really want.
How does fixing fire/poison fields so they don't damage players and NPCs with every step taken in any way create the scenario you're describing above? In my opinion you're exaggerating more than just a bit.
With the current setup, most of the time I don't move a character (who is within an elemental field) out of the field unless that character is extremely close to its borders (i.e. one step away). Instead I roll a heal-over-time on him to offset the per-turn elemental damage (the very thing you seem to be concerned about the gameplay turning into), or I remove the elemental field itself.
I don't understand how allowing the option to move out of the field without taking massive amounts of damage somehow dumbs down or worsens the gameplay in your mind.
The problem I see in responses like yours is that you want these elemental fields to be zones that "must be avoided under penalty of death". In your mind a character running through these fields and taking reasonable damage is just bad game design, but running around these fields.. well that's tactical gameplay at its finest, or something. I disagree.
And that's not even touching on the crazy problems occurring when these fields are suddenly generated at a character's current position (from an enemy archer with a special arrow, for example).
I'm sorry, but the following scenario is ridiculous:
Enemy Archer: <twang>Conan: "<cough> GAS!!"Merlin: "Conan! Get out of the poisonous cloud before it disolves your flesh!"Conan: "NOOO! <cough> I will hold my breath and remain perfectly still until it dissipates! <cough> Now heal me!!"Merlin: "Run out of the cloud!"Conan: "NOO! Cast da heal on me!! <cough> This is a tactically superior maneuver!!"Merlin: "You could have been out of the cloud already!"Conan: "Damn you wizard, cast da heal!!"Merlin: "I have literally killed two of our opponents while you are pretending to be a statue."Conan: "My ear has fallen off!! ARRGHH I will not move! Tactically superior!!"Merlin: "Fight is over. Just gathering loot. Ooo.. a magical sword..!"Conan: "Where?? I am coming! I..ahHHHH <Conan disolves>"Merlin: "Now you move??"..and yet that is pretty much what the current setup encourages.