It's Rare enough that Wizards ever find a chance to use Waterball and have it Be useful outside of having a sage/ninja to supply the water for you. I think it'd be nice to have a DB room that is nothing but water so Wizards can be even more powerful Glass cannons than they already are =x.
Probably because the current db rooms are the old nightmare pvp rooms, and they just don't have water... and I'm honest to say, I'm pretty lazy in map making >>;