They're extras. Of course less priority will be placed on them. Have you, you know, played Soul Calibur III, IV and V? The Extra Characters/CaS-only styles were horrible broken, either unplayable due to being shit or being broken as Hell and therefore automatically banned from tournament play. The rest were lucky to be borderline viable with, like, 3 viable characters throughout all 3 games.
But that's the thing, when do you decide that a character is at a "satisfying place"? Namco Bandai does not use location testing and hire competitive players to beta test their games the way Capcom does with the Street Fighter-series. It's the reason why we needed a Day One patch for SCV to begin with: Their beta testers aren't good enough to adequately balance their games (or even find game-breaking bugs, such as Fuzzy Guarding). This is, after all, the company that decided to, in each successive patch of SCV, nerf a character which started out as a Mid Tier character (Leixia).0
So if a tester says "This character feels like it's a finished character, playable and not broken" and you take their word for it, it could mean they're SCV Nightmare-tier or SCV sub-Z.W.E.I.-tier. Playtesting characters takes hundreds of hours because you have to test out their hitboxes, frames and then how they interact with other characters so that there aren't matchup-specific issues and glitches.
And to do that, you need to pay someone to sit down and do it. CaS-only styles are by definition extras. No company worth its salt is gonna bother paying through the nose to playtest that shit. And if you think that companies don't or shouldn't playtest their game and characters 'til past launch day (now in the age of readily available patching), then what are you doing on a board for competitive fighting game play?