As long as you're in contact with the plasma, it makes perfect sense to me that the burn is re-applied dirctly after cleansing it. It's like trying to dry yourself with a towel while you're still in the pool...
The way I think it's working, is that every tick (second) the system rushes through all dot's and heals. The order of things today, is that the HE is just before the EWP in the que, meaning the EWP will be reapplied instantly after being cleared. If HE had been moved below EWP in the chain of events, it would be cleared instantly after being applied.
In short, you remove your DoT and get a brand new DoT every second! And really, this is all good IMO. It's not like warp plasma is OP or anything, and the way it works makes sense to me.
PS: The EWP animation is slightly smaller than the damage zone. This is total crap, and makes people catch fire without touching the animation. Would be much better if the animation was bigger, and you could brush it without catching fire!