Why? It doesn't break the game and I play the game exclusively with it on all my characters. I like to RP with it. It has shaped my combat encounters since the day I received the game. Is it bad? Sort of. It means you have to rely on your geomancer party members to flood each and every encounter with glorious, delicious poison fields. Mix in Blood Rain and Blood Sucker and you have a viable playthrough WITHOUT a single health potion, with each player having a distinctive role in addition to the two poison spells. But it is also amazingly fun to turn everything a sickly shade of green and cackle as your enemies run in terror of your swamp. (swamp witch metallica reference, anyone?)
As one complaint, however... Skeletons and the future undead race should NOT be healed by poison. They need a different "talent" that is unique to them. The fleshy zombie NPCs and the players with the talent make sense both thematically and in the lore:
+ If you are a ZOMBIE, you have poison instead of BLOOD in your veins, and thus drop fields of POISON when you are struck, not BLOOD. This is why healing spells and potions HARM you: These sources of healing ACTIVELY remove poison when used. This is why it harms the Zombies. THIS MAKES SENSE AND SHOULD NOT BE CHANGED OR REMOVED.
+ Skeletons have no veins, and therefore should NOT benefit from poison. Have them be immune to it, but not HEAL from it.
