Which seems reasonable to me. After all if you are standing in fire and make a step - you will get burned more, because you just stepped onto a burning surface again. Similar with poison-acid kind of a surface.
What you're basically suggesting is that lifting your foot off a burning surface and setting it back down on the same burning surface should cause *more* damage than just leaving your foot glued to the burning surface and not moving it.
That makes no sense. Why should it cause more damage?
If a burning surface does 30 damage per turn:
1) Standing on it for 2 turns should cause 60 damage total.
2) Spending 2 turns walking 20 steps out of it should also cause 60 damage total. Instead, what's happening is you're taking 30x20+60 = good luck with that damage.
