Yes, this is the perfect fix for those types of Abilities.
It'd also be cool for some Abilities to have an altered use from the air, for example; an aerial Soundquake could be a continuous downward echo, letting her hover and Soundquake enemies below her in a more condensed radius. Whether or not that would be desired over a directional ground slam-cast is up for debate.
Can we get a list of all Abilities that cannot be cast in the air? Possibly organized by "remove check", "ground slam candidate", "would like to experiment/get suggestions".
While we're on the note of borrowing mechanics, I think that Ember's Fire Blast could benefit from the aimed-casting mechanics of Limbo's Cataclysm.