Well OF COURSE I want this feature - and every feature - in the game for me to play with as soon as possible. However, that's just me being an impatient doofus. I want it now, but I don't want it rushed.
Add the feature when it's ready; both in terms of the art assets and for the story. I'll still wake up every morning wondering if it's here yet, but I can wait.
As for whether or not the alternate forms will be "worth it" on a per player basis, ultimately it comes down to personal preference. I may never care about an alternate form for Cleos, because she's already perfect in every possible way, but other players will think differently. But if it is important for the story, then even I will invest in those alternate forms for Cleos, because that matters to me more.