Not every single spell has to be super useful in every.single.situation.
Think of Lethargy on BLM or the water spell on WHM - the only time you ever use them is when you have to keep an enemy away from yourself or the group at all costs, either by slowing it down or kicking it away. The potency doesn't matter since the only reason that spell is cast is for it's movement slowing effect.

So yes, I like Stella just the way it is