I added more to my original post, clarifying some existing details and providing more thoughts on various talking points, such as the few problematic talents in the Elune’s Chosen tree and the major class- and spec-wide issues Balance faces, including survivability and ramp-up time.
With the potential Moonfire has in this tree, dealing significantly more damage from various Arcane bonuses and increasing its Astral Power generation, it’s very possible they intend for Moonfire to be our instant filler during periods of high movement.
Otherwise, if they really want us sitting in Lunar Eclipse (given the theme and aesthetic of the tree) and casting Starfire as our primary filler, they could at least address its lengthy cast by doing something like this:
Plus, adding an effect to this talent that reduces its cast time makes it a more competitive option in that choice node with Stellar Command.
Unfortunately, I don’t see a world where Stellar Drift makes a return even in the form of a kiss/curse. At best, if it were to return, it would probably read like one of the following:
Stellar Drift
Starfall allows you to cast while moving while it is active, but reduces all damage you deal while moving by x%.
Stellar Drift
Starfall allows you to cast while moving while it is active, but reduces the damage it deals by x%.
No downtime here, but at the cost of a moderate amount damage (as you suggested).
It could, however, work as a utility choice node with the other option being mobility, such as Displacer Beast or significantly reducing the cooldown of an existing movement speed ability. I imagine they would need to have a Guardian-equivalent effect, though.