They didn't fix this because they realised that it's better this way. Usually you wouldn't use that anyway for its lack of damage. It would've taken two casts or a units ability and a cast to get this thing to work only to realise eventually that it does far less damage than a regular area damage spell such as Fire Rain. Plus you would have to move your melee units out of the way, and so on and so forth. Waaaaaay too much work for a simple area spell.
Therefore it made sense to leave it that way. Not changing the spell description is just laziness tho
We see that in many other spells and abilities in the game, too.